Patent Application
20080088222
The invention will be described in detail with reference to the following drawings in which like numerals refer to like elements.
a and
a and
a and
a to 9d illustrate a dispensing characteristic of a phosphor according to one embodiment.
a and 12b illustrate modifications of a rising signal and a second falling signal of
A plasma display panel of the present invention will be described below with reference to the accompanying drawings.
Referring to
The upper dielectric layer 104 for covering the first electrode 102 and the second electrode 103 is formed on an upper portion of the front substrate 101 on which the first electrode 102 and the second electrode 103 are formed.
The upper dielectric layer 104 limits discharge currents of the first electrode 102 and the second electrode 103, and the upper dielectric layer 104 provides insulation between the first electrode 102 and the second electrode 103.
A protective layer 105 is formed on an upper surface of the upper dielectric layer 104 to facilitate discharge conditions. The protective layer 105 may be formed by deposing a material such as magnesium oxide (MgO) on an upper portion of the upper dielectric layer 104.
A lower dielectric layer 115 for covering the third electrode 113 is formed on an upper portion of the rear substrate 111 on which the third electrode 113 is formed. The lower dielectric layer 115 provides insulation of the third electrode 113.
Barrier ribs 112 are formed on an upper portion of the lower dielectric layer 115 to partition discharge cells.
A phosphor (i.e., red phosphor, green phosphor, blue phosphor) is formed inside the discharge cells to display colors.
In addition to the red (R), green (G), and blue (B) phosphors, a white (W) phosphor or a yellow (Y) phosphor may be further formed inside the discharge cells.
A structure of discharge cells in which is formed by barrier ribs may be a various type such as stripe type, a well type, a delta type, a honey type.
Both widths (a), (b), (c) of the red (R), green (G), and blue (B) discharge cells may be substantially equal to one another and each of the width of discharge cells may be controlled so as to improve a user's visibility when it is displayed an image on the screen of a plasma display panel.
In this case, as illustrated in
The plasma display panel according to one embodiment may have various forms of barrier rib structures as well as a structure of the barrier rib 112 illustrated in
a and
Referring to
In this case, if a height of the first barrier rib 112a is more than a height of the second barrier rib 112b, the first barrier rib 112a partitions the discharge cells which contain a different phosphor therein and the second barrier rib 112b partitions the discharge cells which contain a same phosphor therein, respectively.
And thus, the structure of barrier rib improves a characteristic of exhaust of a plasma display panel when the plasma display panel is manufactured and prevents a color of phosphor in one discharge cell from being mixed by a phosphor in another discharge cell when the phosphor is formed into the discharge cell.
A difference of the height (h2) of the first barrier rib 112a and the height (h1) of the second barrier rib 112b ranges from 10 μm to 35 μm in the active area which is displayed an image.
And thus, when the plasma display panel has the barrier ribs 112a, 112b which have a different height each other in the critical value of the difference of the height between the barrier ribs 112a, 112b, the plasma display panel has a characteristic of exhaust improved as well as a strong property of barrier rib improved.
Referring to
As a result, a structure of the barrier rib improves a characteristic of exhaust of the plasma display panel.
Although the barrier rib 112 is formed over the rear substrate 111 in the embodiment of the invention, the barrier rib 112 may be formed over the front substrate 101 of the plasma display panel.
Referring to
In this case, the thickness (t1) of the red phosphor layer may be less than each thickness (t2, t3) of the green phosphor layer and the blue phosphor layer.
At least one of a thickness (t3) of the blue phosphor layer and a thickness (t2) of the green phosphor layer which is more than a thickness (t1) of the red phosphor layer ranges from 2 μm to 3 μm.
And thus, when the plasma display panel is manufactured in critical thickness of the phosphor layer, the plasma display panel increases an efficiency of a luminescent as well as a characteristic of color temperature of the phosphor.
Furthermore, the thickness (t2) of the green phosphor may be substantially equal to or may be different from the thickness (t3) of the blue phosphor.
It must be noted that only one example of the plasma display panel according to one embodiment has been illustrated and described above, and the embodiment is not limited to the plasma display panel of the above-described structure. For instance, although the above description illustrates a case where the upper dielectric layer 104 and the lower dielectric layer 115 each are formed in the form of a single layer, at least one of the upper dielectric layer 104 and the lower dielectric layer 115 may be formed in the form of a plurality of layers.
A black layer (not shown) for absorbing external light may be further formed on the upper portion of the barrier ribs 112 to prevent the reflection of the external light caused by the barrier ribs 112.
Further, a black layer (not shown) may be further formed at a predetermined position on the front substrate 201 corresponding to the barrier ribs 112.
The third electrode 113 formed on the rear substrate 211 may have a substantially constant width or thickness. Further, the width or thickness of the third electrode 113 inside the discharge cell may be different from the width or thickness of the third electrode 113 outside the discharge cell. For instance, the width or thickness of the third electrode 113 inside the discharge cell may be more than the width or thickness of the third electrode 113 outside the discharge cell.
In this way, the structure of the plasma display panel of the plasma display apparatus according to one embodiment may be changed in various ways.
a and 5b illustrate a structure of electrode of a plasma display panel according to one embodiment.
Referring to
For instance, each of the first electrode 102 and the second electrode 103 includes bus electrodes 102b and 103b and transparent electrodes 102a. To emit light generated inside the discharge cells to the outside and secure the driving efficiency, the bus electrodes 102b and 103b include a material with high electrical conductivity such as silver (Ag), and the transparent electrodes 102a and 103a include a transparent material such as indium-tin-oxide (ITO).
When each of the first electrode 102 and the second electrode 103 includes the bus electrodes 102b and 103b and the transparent electrodes 102a and 103a, each of black layers 220 and 221 may be further formed between the bus electrode 102b and 103b and the transparent electrode 102a and 103a to prevent the reflection of external light caused by the bus electrodes 102b and 103b.
Referring to
Each of the first electrode 102 and the second electrode 103 may contain an opaque and conductive materials such as silver (Ag), copper (Cu), aluminum (Al) or contain an transparent materials such as indium tin oxide (ITO).
And thus, it is easy to manufacture the first electrode 102 and the second electrode 103 such that the manufacturing cost is reduced.
The first electrode 102 and the second electrode 103 may be darker than a color of the upper dielectric layer 104.
Each of black layers 300a, 300b may be formed between the first electrode 102 and the front substrate 101 and between the second electrode 103 and the front substrate 101, respectively.
In this case, each of black layers 300a, 300b includes ruthenium (Ru) with dark color
And thus, the black layers 300a, 300b prevent the first electrode 102 and the electrode 103 from changing a characteristic of the electrodes 102, 103.
(i.e., the changing of a characteristic of the electrode is defined as migration phenomenon of an electrode.)
Furthermore, the black layers 300a, 300b decrease a reflection ratio of a ray of light incident from outer space of the plasma display panel such that a characteristic of contrast is improved.
Referring to
A phosphor layer 420 which is formed over the substrate includes a red phosphor layer, a green phosphor layer and a blue phosphor layer. In this case, at least one of a start point of the red phosphor layer, the green phosphor layer and the blue phosphor layer is different from a start point of the remaining phosphor layer.
The start point of the red phosphor layer, the green phosphor layer and the blue phosphor layer may be different from one another respectively.
The start point of the blue phosphor layer 420a may be prior to the start point of the red phosphor layer 420c and the start point of the green phosphor layer 420b from an edge of the substrate, or the start point of the green phosphor layer 420b may be prior to the start point of the red phosphor layer 420c from an edge of the substrate.
In this case, a position of the start point of the phosphor layers is positioned on the dummy area 400 of the substrate.
A distance between an edge of the barrier rib 430 and an edge of the blue phosphor layer 420a is defined as a first distance (d1) and a distance between an edge of the barrier rib 430 and an edge of the green phosphor layer 420b is defined as a second distance (d2) and a distance between an edge of the barrier rib 430 and an edge of the red phosphor layer 420c is defined as a third distance (d3).
In this case, the first distance (d1), the second distance (d2) and the third distance (d3) may be different from one another respectively.
Furthermore, as described in
As described in
At least one of a length (L1) of a blue phosphor layer 420a, a length (L2) of a green phosphor layer 420b and, a length (L3) of red phosphor layer 420c may be different from the length of the remaining phosphor layer on the substrate.
For example, as described in
A difference among a blue phosphor layer, a green phosphor layer and a red phosphor layer may be applied to the phosphor layers which are formed in a dummy area of the substrate.
Meanwhile, a dielectric layer (not shown) which is formed on the substrate may include a first portion of the dielectric layer, a second portion of the dielectric layer and a third portion of the dielectric layer.
The first portion of the dielectric layer, the second portion of the dielectric layer and the third portion of the dielectric layer is corresponded to the red phosphor layer, the green phosphor layer and the blue phosphor layer, respectively. And each the first portion of the dielectric layer, the second portion of the dielectric layer and the third portion of the dielectric layer is an area where the phosphor is not formed thereon.
In this case, at least one of a length of a first portion of the dielectric layer, a length of a second portion of the dielectric layer and a length of a third portion of the dielectric layer is different from a length of the remaining portion of the dielectric layer,
a to 9d illustrate a dispensing characteristic of a phosphor according to one embodiment.
Referring to
The dispensing apparatus 500 dispenses the material (i.e., a paste or a slurry) of a phosphor through a nozzle 510 into discharge cells which is partitioned by barrier rib 112.
After that, the paste of the phosphor is dried and plasticized. As a result, the phosphor layer is formed.
Meanwhile, when the material of a phosphor is dispensed into the discharge cells, the difference between circumstances (i.e., temperature) of inner space of the nozzle 510 and circumstances of outer space of the nozzle 510 cause a material of the phosphor to be dispensed into the discharge cells non-uniformly at the beginning period of dispensing.
Therefore, as described in
The duration of the beginning period of dispensing the material of phosphors is different from one another according to a characteristic of the material of phosphors. That is, as described in
Accordingly, it is necessary that the starting point of dispensing of the phosphors is controlled to dispense the material of phosphors uniformly on the same active area of the substrate. That is, the dispensing apparatus sets the start point of dispensing the blue phosphor layer to be prior to the start point of dispensing the green phosphor and dispensing the red phosphor from the edge of the barrier rib.
As described in
Because a structure of the barrier rib 550 of the above allows the dispensing apparatus 500 to detect the barrier rib 550 easily at the side portion of the barrier rib so that the dispensing apparatus 500 may accurately control a starting point of dispensing the material of phosphors.
Furthermore, a structure of the barrier rib which is described in
Referring to
Each subfield is subdivided into a reset period for initializing all the discharge cells, an address period for selecting cells to be discharged, and a sustain period for representing gray level in accordance with the number of discharges.
The number of subfields constituting one frame may vary with a gray level to be represented.
For example, if an image with 256-level gray level is to be displayed, the frame is divided into 8 subfields SF1 to SF8. The number of sustain signals supplied during a sustain period of each subfield determines gray level weight in each subfield.
For example, in such a method of setting gray level weight of a first subfield to 20 and setting gray level weight of a second subfield to 21, the sustain period increases in a ratio of 2n (where, n=0, 1, 2, 3, 4, 5, 6, 7) in each of the subfields. Since the sustain period varies from one subfield to the next subfield, a specific gray level is achieved by controlling the sustain period which are to be used for discharging each of the selected cells, i.e., the number of sustain discharges that are realized in each of the discharge cells.
Although
Referring to
The first falling signal supplied to the first electrode Y gradually falls to a first voltage V10.
A voltage Vpz of the pre-sustain signal (Psus) is substantially equal to a voltage Vs of a sustain signal (Sus) which will be supplied during a sustain period.
As above described, the first falling signal is supplied to the first electrode Y and the pre-sustain signal is supplied to the second electrode Z during the pre-reset period such that wall charges of a predetermined polarity are accumulated on the first electrode Y and wall charges of a polarity opposite the polarity of the wall charges accumulated on the first electrode Y are accumulated on the second electrode Z. For example, wall charges of a positive polarity are accumulated on the first electrode Y, and wall charges of a negative polarity are accumulated on the second electrode Z.
As a result, the initialization of all the discharge cells formed in the plasma display panel is stably performed during the reset period which follows the pre-reset period.
Further, even if a rising signal having a relatively low voltage is supplied to the first electrode Y during the reset period, the initialization of all the discharge cells is stably performed.
A first subfield in a plurality of subfields of one frame may include a pre-reset period prior to a reset period. The first and second subfields or the first, second and third subfields in the plurality of subfields may include a pre-reset period prior to a reset period.
Each subfield may not include the pre-reset period.
During the reset period which follows the pre-reset period, a rising signal and a second falling signal are supplied to the first electrode Y and a positive polarity signal (Sp) is supplied to the second electrode Z.
The rising signal includes a first rising signal and a second rising signal. The first rising signal gradually rises from a second voltage V20 to a third voltage V30 with a first slope, and the second rising signal gradually rises from the third voltage V30 to a fourth voltage V40 with a second slope.
The second slope of the second rising signal is gentler than the first slope of the first rising signal. When the second slope is gentler than the first slope, the quantity of light generated by a setup discharge is reduced such that contrast of the plasma display apparatus is improved.
The positive polarity signal (Sp) is supplied to the second electrode Z during the supplying of the rising signal or before an end time point of the rising signal.
It may be that the width of the positive polarity signal (Sp) is smaller than the width of a sustain signal having the widest width in the plurality of sustain signals supplied to at least one of the first electrode or the second electrode during the sustain period.
A magnitude (ΔV) of a voltage of the positive polarity signal (Sp) is substantially equal to a magnitude (ΔVs) of the voltage of the sustain signal (Sus) supplied to at least one of the first electrode or the second electrode during the sustain period. During a setup period of the reset period, the rising signal generates a weak setup discharge inside the discharge cells, thereby accumulating a predetermined amount of wall charges inside the discharge cells.
The positive polarity signal (Sp) reduces the amount of wall charges excessively accumulated inside the discharge cells, thereby reducing the generation of an erroneous discharge during the address period and the sustain period.
During a set-down period of the reset period, the second falling signal of a polarity opposite a polarity of the rising signal is supplied to the first electrode Y.
The second falling signal gradually falls from the second voltage V20 to a fifth voltage V50. The second falling signal generates a weak erase discharge (i.e., a set-down discharge) inside the discharge cells. Furthermore, the remaining wall charges are uniform inside the discharge cells to the extent that an address discharge can be stably performed.
During the address period, a scan bias signal, which gradually rises from the fifth voltage V50 to a voltage Vyb and then is maintained at the voltage Vyb, is supplied to the first electrode Y. A scan signal (Scan), which falls from the voltage Vyb of the scan bias signal by a scan voltage magnitude ΔVy, is supplied to all the first electrodes Y1 to Yn.
In this case, the width of the scan signal (Scan) may vary from one subfield to the next subfield. For example, the width of a scan signal in a subfield may be more than the width of a scan signal in the next subfield.
When the scan signal (Scan) is supplied to the first electrode Y, a data signal (Data) corresponding to the scan signal (Scan) is supplied to the third electrode X. The data signal (Data) rises from a ground level voltage GND by a data voltage magnitude ΔVd.
As the voltage difference between the scan signal (Scan) and the data signal (Data) is added to the wall voltage generated during the reset period, the address discharge occurs within the discharge cells to which the data signal (Data) is supplied.
A sustain bias signal is supplied to the second electrode Z during the address period to prevent the generation of the unstable address discharge.
The sustain bias signal is supplied to the second electrode Z after the passage of a predetermined duration of time from the supplying of the positive polarity signal (Sp). In this case, a duration of time ranging from an end time point of the supplying of the positive polarity signal (Sp) to a start time point of the supplying of the sustain bias signal is longer than the width of the positive polarity signal (Sp).
When the width of the positive polarity signal (Sp) is set to a, and the duration of time ranging from the end time point of the supplying of the positive polarity signal (Sp) to the start time point of the supplying of the sustain bias signal is set to b, a ratio (b/a) of “b” to “a” is more than 1 and is equal to or less than 10. In this case, stable discharges occur during the reset period and the address period.
A supply time point of the sustain bias signal may correspond to a supply time point of the scan bias signal. Although it is not illustrated in the attached drawings, the sustain bias signal may be supplied to the second electrode Z during the set-down period or near the beginning of the address period.
A voltage Vzb of the sustain bias signal is lower than the voltage of the sustain signal which will be supplied during the sustain period, and is higher than the ground level voltage GND. Further, the voltage Vzb of the sustain bias signal is lower than the positive polarity signal (Sp).
During the sustain period, a sustain signal (Sus) is alternately supplied to the first electrode Y and the second electrode Z.
As the wall voltage within the discharge cell selected by performing the address discharge is added to a sustain voltage Vs of the sustain signal (Sus), every time the sustain signal (Sus) is supplied, a sustain discharge, i.e., a display discharge occurs between the first electrode Y and the second electrode Z.
a and 12b illustrate modifications of a rising signal and a second falling signal of
Referring to
As above, the slope of the rising signal may vary.
Referring to
a voltage falling time point of the second falling signal is changeable.
Referring to
The bias signal is maintained at the ground level voltage GND.
when the sustain signal is supplied to either the first electrode Y or the second electrode Z, a single diving board for driving the first electrode Y and the second electrode Z during the sustain period may be installed.
Accordingly, the whole size of a driver for driving the plasma display panel is reduced such that the manufacturing cost is reduced.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2006-0100544 | Oct 2006 | KR | national |
