This application claims the benefit of Korean Patent Application No. 010-2007-0106185 filed on Oct. 22, 2007, which is hereby incorporated by reference.
1. Field
This document relates to a plasma display panel.
2. Description of the Background Art
A plasma display panel includes a phosphor layer inside discharge cells partitioned by barrier ribs and a plurality of electrodes.
When driving signals are applied to the electrodes of the plasma display panel, a discharge occurs inside the discharge cells. In other words, when the plasma display panel is discharged by applying the driving signals to the discharge cells, a discharge gas filled in the discharge cells generates vacuum ultraviolet rays, which thereby cause phosphors positioned between the barrier ribs to emit light, thus producing visible light. An image is displayed on the screen of the plasma display panel due to the visible light.
In one aspect, a plasma display panel comprises a front substrate, a rear substrate positioned opposite the front substrate, a barrier rib positioned between the front substrate and the rear substrate to partition a discharge cell, and a phosphor layer positioned in the discharge cell, the phosphor layer including a phosphor material and an additive material, wherein the discharge cell includes a red discharge cell, a green discharge cell, and a blue discharge cell, and a width of the blue discharge cell is larger than a width of the red discharge cell based on a lower part of the barrier rib.
In another aspect, a plasma display panel comprises a front substrate on which a scan electrode and a sustain electrode are positioned parallel to each other, a rear substrate on which an address electrode is positioned to intersect the scan electrode and the sustain electrode, a barrier rib positioned between the front substrate and the rear substrate to partition a discharge cell, and a phosphor layer positioned in the discharge cell, the phosphor layer including a phosphor material and an additive material, wherein the discharge cell includes a red discharge cell, a green discharge cell, and a blue discharge cell, and an interval between the address electrode of the blue discharge cell and the address electrode of the green discharge cell is wider than an interval between the address electrode of the red discharge cell and the address electrode of the green discharge cell.
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated on and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings:
Reference will now be made in detail embodiments of the invention examples of which are illustrated in the accompanying drawings.
As shown in
An upper dielectric layer 104 may be positioned on the scan electrode 102 and the sustain electrode 103 to limit a discharge current of the scan electrode 102 and the sustain electrode 103 and to provide electrical insulation between the scan electrode 102 and the sustain electrode 103.
A protective layer 105 may be positioned on the upper dielectric layer 104 to facilitate discharge conditions.
A lower dielectric layer 115 may be positioned on the address electrode 113 to cover the address electrode 113 and to provide electrical insulation of the address electrodes 113.
Barrier ribs 112 of a stripe type, a well type, a delta type, a honeycomb type, and the like, may be positioned on the lower dielectric layer 115 to partition discharge spaces (i.e., discharge cells). A red discharge cell emitting red (R) light, a blue discharge cell emitting blue (B) light, and a green discharge cell emitting green (G) light, and the like, may be positioned between the front substrate 101 and the rear substrate 111.
A phosphor layer 114 may be positioned inside the discharge cells partitioned by the barrier ribs 112 to emit visible light for an image display during an address discharge. For instance, red, green, and blue phosphor layers that emit red, green, and blue light, respectively, may be positioned inside the discharge cells.
In the related art plasma display apparatus, red, green, and blue discharge cells each have an equal length and an equal width, and phosphor layers coated on the red, green, and blue discharge cells have a different discharge characteristic.
Although discharges having an equal intensity occur inside the red, green, and blue discharge cells, magnitudes (i.e., gray scale) of red, green, and blue light emitted from the red, green, and blue discharge cells are different from one another. Therefore, it is difficult to balance the red, green, and blue light, and thus it is difficult to achieve full white.
In other words, because red, green, and blue phosphor layers coated on the symmetrically positioned discharge cells with the barrier rib interposed therebetween have a different light emitting characteristic, the red, green, and blue discharge cells generating red, green, and blue light have a different light emitting luminance. Therefore, white balance (i.e., the correction of a color temperature) is necessary so as to achieve pure white light.
As shown in
As above, when the width W3 of the blue discharge cell 220 is larger than the width W1 of the red discharge cell 200, the amount of blue light emitted from the blue discharge cell 220 may increase. Hence, a color temperature of a displayed image can be improved.
The amount of light produced by the green phosphor layer 114G is more than the amount of light produced by the red and blue phosphor layers 114R and 114B at an equal voltage. Accordingly, the width W3 of the blue discharge cell 220 may be larger than the width W1 of the red discharge cell 200, so as to improve the color temperature of the displayed image and to prevent a reduction in the luminance.
Because the width W3 of the blue discharge cell 220 is larger than the width W1 of the red discharge cell 200, an interval T2 between an address electrode 113b of the blue discharge cell 220 and an address electrode 113g of the green discharge cell 210 may be wider than an interval T1 between an address electrode 113r of the red discharge cell 200 and the address electrode 113g of the green discharge cell 210, so as to position the address electrodes 113r, 113g, and 113b in the center of each discharge cell 200, 210, and 220.
As shown in
When the ratio W3/W1 is 1.01, the color temperature increases to approximately 7,080K.
When the ratio W3/W1 is 1.05, the color temperature is approximately 7,160K.
When the ratio W3/W1 ranges from 1.06 to 1.25, the color temperature has a relatively high value of approximately 7,310K to 7,690K.
When the ratio W3/W1 is 1.4, the color temperature is approximately 7,790K. When the ratio W3/W1 is 1.5, the color temperature is approximately 7,800K.
As the ratio W3/W1 increases, the amount of blue light generated in the blue discharge cell increases. Hence, the color temperature increases. On the other hand, when the ratio W3/W1 is equal to or more than 1.5, an increase width of the color temperature is small even if the ratio W3/W1 increases.
As shown in
When the ratio W3/W1 ranges from 1.25 to 1.40, the color representability is good (◯).
On the other hand, when the ratio W3/W1 is 1.50, the width W1 of the red discharge cell may be excessively smaller than the width W3 of the blue discharge cell. Hence, the representability of all colors of an image may be bad.
Considering the description of
As shown in (a) and (b) of
For instance, it is assumed that (Y, Gd)BO:Eu used as a red phosphor material emitting red light is positioned in the red discharge cell 200, Zn2SiO4:Mn+2 or YBO3:Tb+3 used as a green phosphor material emitting green light is positioned in the green discharge cell 210, and (Ba, Sr, Eu)MgAl10O17 used as a blue phosphor material emitting blue light is positioned in the blue discharge cell 220. (Y, Gd)BO:Eu, Zn2SiO4:Mn+2 or YBO3:Tb+3, and (Ba, Sr, Eu)MgAl10O17 may have a different electrical characteristic such as permittivity, secondary electron emission coefficient, electron affinity.
Accordingly, as shown in (a) of
As above, the phosphor layer may include an additive material (for example, MgO material) so as to remove a difference among discharge characteristics of the discharge cells.
As shown in
The particles 1010 of the additive material can improve a discharge response characteristic between the scan electrode and the address electrode or between the sustain electrode and the address electrode. This will be below described in detail.
In case that the phosphor layer 114 includes the additive material such as MgO, the particles of the additive material act as a catalyst of a discharge. Hence, a discharge can stably occur between the scan electrode and the address electrode at a relatively low voltage. Accordingly, before a strong discharge occurs at a relatively high voltage in a specific portion of the phosphor layer 114, on which charges are concentratedly accumulated, a discharge can occur at a relatively low voltage in a portion of the phosphor layer 114, on which the particles of the additive material are positioned. This is because particles of the additive material having a relatively high secondary electron emission coefficient emit a large amount of electrons during a discharge.
Referring again to
The additive material may include at least one of magnesium oxide (MgO), zinc oxide (ZnO), silicon oxide (SiO2), titanium oxide (TiO2), yttrium oxide (Y2O3), aluminum oxide (Al2O3), lanthanum oxide (La2O3), europium oxide (EuO), cobalt oxide, iron oxide, or CNT (carbon nano tube). It may be advantageous that the additive material is MgO material.
At least one of the particles 1000 of the phosphor material on the surface of the phosphor layer 114 may be exposed in a direction toward the center of the discharge cell. For instance, since the particles 1010 of the additive material are disposed between the particles 1000 of the phosphor material on the surface of the phosphor layer 114, at least one particle 1000 of the phosphor material may be exposed.
As described above, when the particles 1010 of the additive material are disposed between the particles 1000 of the phosphor material, a discharge response characteristic between the scan electrode and the address electrode or between the sustain electrode and the address electrode can be improved. Further, since the surface area of the particles 1000 of the phosphor material covered by the particles 1010 of the additive material may be minimized, a reduction in a luminance can be prevented.
As shown in
For instance, as shown in (a) of
The structure of
For instance, in case that the amount of charges accumulated on the surface of the blue phosphor layer 114B is less than the amount of charges accumulated on the surface of the red phosphor layer 114R, a discharge in the blue phosphor layer 114B may occur later than a discharge in the red phosphor layer 114R. However, in this case, because the blue phosphor layer 114B includes the particles 1010 of the additive material, a discharge can earlier occur in the blue phosphor layer 114B. Hence, the discharge can uniformly occur in the red phosphor layer 114R and the blue phosphor layer 114B.
As shown in
Next, the prepared additive power is mixed with a solvent in step S1110. For instance, the resulting MgO powder is mixed with methanol to manufacture an additive paste or an additive slurry. A binder may be added so as to adjust a viscosity of the additive paste or the additive slurry.
Subsequently, the additive paste or the additive slurry is coated on the phosphor layer in step S1120. In this case, a viscosity of the additive paste or the additive slurry is adjusted so that particles of the additive material are smoothly positioned between particles of the phosphor material.
Subsequently, a dry process or a firing process is performed in step S1130. Hence, the solvent mixed with the additive material is evaporated to form the phosphor layer of
In the comparative example, the phosphor layer does not include an additive material.
In the experimental example 1, the phosphor layer includes MgO material of 3% based on the volume of the phosphor layer as an additive material.
In the experimental example 2, the phosphor layer includes MgO material of 9% based on the volume of the phosphor layer as an additive material.
In the experimental example 3, the phosphor layer includes MgO material of 12% based on the volume of the phosphor layer as an additive material.
In the comparative example, the firing voltage is 135V, and the luminance is 170 cd/m2.
In the experimental examples 1, 2 and 3, the firing voltage is 127V to 129V lower than the firing voltage of the comparative example, and the luminance is 176 cd/m2 to 178 cd/m2 higher than the luminance of the comparative example. Because the particles of the MgO material as the additive material in the experimental examples 1, 2 and 3 act as a catalyst of a discharge, the firing voltage between the scan electrode and the address electrode is lowered. Furthermore, in the experimental examples 1, 2 and 3, because an intensity of a discharge generated at the same voltage as the comparative example increases due to a fall in the firing voltage, the luminance further increases.
While the bright room contrast ratio of the comparative example is 55:1, the bright room contrast ratio of the experimental examples 1, 2 and 3 is 58:1 to 61:1. As can be seen from
In the experimental examples 1, 2 and 3, a discharge uniformly occurs at a lower firing voltage than the firing voltage of the comparative example, and thus the amount of light during a reset period is relatively small.
In
As shown in (b) of
As shown in (a) of
The address discharge delay time means a time interval between a time point when the scan signal and the data signal are supplied to the scan electrode and the address electrode during an address period, respectively and a time point when an address discharge occurs between the scan electrode and the address electrode.
As shown in
When the volume percentage of the MgO material is 2%, the discharge delay time is reduced to be approximately 0.75 μs. In other words, because the particles of the MgO material improve a discharge response characteristic between the scan electrode and the address electrode, an address jitter characteristic can be improved.
Further, when the volume percentage of the MgO material is 5%, the discharge delay time may be approximately 0.72 μs. When the volume percentage of the MgO material is 6%, the discharge delay time may be approximately 0.63 μs.
When the volume percentage of the MgO material lies in a range between 10% and 50%, the discharge delay time may be reduced from approximately 0.55 μs to 0.24 μs.
It can be seen from the graph of
On the other hand, in case that the volume percentage of the MgO material is excessively large, the particles of the MgO material may excessively cover the surface of the particles of the phosphor material. Hence, a luminance may be reduced.
Accordingly, the percentage of the volume of the MgO material based on the volume of the phosphor layer may lie substantially in a range between 2% and 40% or between 6% and 27% so as to reduce the discharge delay time and to prevent an excessive reduction in the luminance.
As shown in
When the particles 1010 of the additive material may be positioned on the surface of the phosphor layer 114, inside the phosphor layer 114, and between the phosphor layer 114 and the lower dielectric layer 115, a discharge response characteristic between the scan electrode and the address electrode or between the sustain electrode and the address electrode can be improved.
As shown in
The prepared additive power is mixed with phosphor particles in step S1610.
The additive power and the phosphor particles are mixed with a solvent in step S1620.
The additive power and the phosphor particles mixed with the solvent are coated inside the discharge cells in step S1630. In the coating process, a dispensing method may be used.
A dry process or a firing process is performed in step S1640 to evaporate the solvent. Hence, the phosphor layer having the structure shown in
The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. The description of the foregoing embodiments is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art.
Number | Date | Country | Kind |
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10-2007-0106185 | Oct 2007 | KR | national |