Patent Application
20070285356
The invention will be described in detail with reference to the following drawings in which like numerals refer to like elements.
Preferred embodiments of the present invention will be described in a more detailed manner with reference to the drawings.
Referring to
The upper panel 200 includes sustain electrodes 202 and 203 formed on an upper substrate 201 by pair. The sustain electrode pair 202 and 203 are classified into a scan electrode 202 and a sustain electrode 203 depending on its function. The sustain electrode pair 202 and 203 is covered by a upper dielectric layer 204 for limiting a discharge current and insulating between the electrode pair. A protective layer 205 is formed on the upper dielectric layer 204. The protective layer 205 protects the upper dielectric layer 204 from sputtering of charged particles generated at the time of gas discharge and enhances an emission efficiency of secondary electrons.
The lower panel 210 includes barrier ribs 212a and 212b formed on the lower substrate 211 for partitioning a plurality of discharge spaces, that is, discharge cells. Address electrodes 213 are arranged in the direction of intersecting with the sustain electrode pair 202 and 203. A phosphor layer 214 is coated on the barrier ribs 212a and 212b and the lower dielectric layer 215. The phosphor layer 214 is excited by ultraviolet rays generated in the gas discharge, and generates visible rays.
The barrier ribs 212a and 212b include vertical barrier ribs 212a formed in parallel with the address electrodes 213, and horizontal barrier ribs 212b formed in the direction of intersecting with the address electrodes 213. The barrier ribs 212a and 212b physically divide the discharge cells and prevent ultraviolet ray and visible ray from leaking to adjacent discharge cells.
In the plasma display panel according to the present embodiment, the sustain electrode pair 202 and 203 are formed of only opaque metal electrodes unlike the conventional sustain electrode pair 102 and 103 shown in
For example, in the present embodiment, it is desirable that each of the sustain electrode pair 202 and 203 is made of silver having a photosensitive property. Also, it is desirable that each of the sustain electrode pair 202 and 203 according to the embodiment of the present invention has a property of darker color and lower light transmission than those of the upper dielectric layer 204 formed on the upper substrate 201.
It is desirable that the thickness of electrode lines 202a, 202b, 203a and 203b have thicknesses of about 2 μm to 8 μm. When the electrode lines 202a, 202b, 203a and 203b having thicknesses of the above range can provide a resistance range and an aperture ratio making a normal operation of the plasma display panel possible. Thus, the electrode lines can be prevented from blocking lights reflected and coming out from a front surface of plasma display apparatus, and decreasing a luminance. Also, a capacitance of the plasma display panel does not greatly increase. It is desirable that the electrode lines 202a, 202b, and 203a, 203b have resistances of about 50 to 60Ω, having thicknesses of about 2 μm to 8 μm.
The respective red (R), green (G), and blue (B) phosphor layers 214 can be equal to or different from each other in width. When the phosphor layers 214 of the R, G, B discharge cells are different from each other in width, the phosphor layer 214 of the G or B discharge cell can be greater in width than the phosphor layer 214 of the R discharge cell.
As shown in
This considers the aperture ratio and a discharge diffusion efficiency according to the use of the opaque sustain electrode pair 202 and 203. In order words, the first and second sustain electrodes 202 and 203 use the electrode lines of narrow widths considering the aperture ratio, and uses the electrode lines in plural considering the discharge diffusion efficiency. It is desirable that the number of the electrode lines is decided considering the aperture ratio and the discharge diffusion efficiency at the same time.
Each of the electrode lines 202a, 202b, 203a and 203b can be formed on a predetermined black layer (not shown), not in direct contact with the upper substrate 201. In other words, the black layer can be formed between the upper substrate 201 and the respective electrode lines 202a, 202b, and 203a, 203b, thereby improving a discoloration phenomenon of the upper substrate 201, which is caused by a direct contact between the upper substrate 201 and the respective electrode lines 202a, 202b, and 203a, 203b.
The structure of the plasma display panel of
In formation, the black matrix can be formed at the same time with the black layer to be physically connected, or can be formed at a different time from the black layer to be physically disconnected. In case of forming the black matrix and the black layer to be physically connected, the black matrix and the black layer are formed using the same material. On the contrary, in case of forming the black matrix and the black layer to be physically disconnected, different materials are used.
Although
Also, the barrier ribs may be formed in various shapes in addition to the barrier rib structure shown in
Although the R, G, and B discharge cells are formed on the same line in the present embodiment, the R, G and B discharge cells may be arranged in a different shape. For example, the R, G and B discharge cells can be arranged in a triangle shape, that is, a delta type. Also, the R, G and B discharge cells can be arranged in a rectangle shape, a pentagon shape, and a hexagonal shape.
Also, the widths of the vertical barrier ribs 212a and the horizontal barrier ribs 212b may be different from each other, and the width of the barrier ribs may be a top width or a bottom width. Also, it is desirable that the width of the horizontal barrier rib 212b is about 1.0 to 5.0 times of the width of the vertical barrier wall 212a.
In the plasma display panel according to the present embodiment, the pitches of the R, G and B discharge cells in the plasma display panel according to the present embodiment are substantially identical. However, the R, G, and B discharge cells can also have different pitches to adjust a color temperature in the R, G, and B discharge cells. The R, G, B discharge cells can all have different pitches, but only the discharge cell expressing one color among the R, G, B discharge cells can have a different pitch. For example, it is possible that the R discharge cell has the smallest pitch, and the G and B discharge cells have greater pitches than the R discharge cell.
Although the address electrodes formed on the lower substrate 211 can be substantially constant in width or thickness, a width or thickness of the address electrodes within the discharge cell can be different from the that of the outside of the discharge cell. For example, its width or thickness within the discharge cell can be greater than that of the outside of the discharge cell.
It is desirable that the barrier rib 121 does not uses lead (Pb), or contains, though any, less lead (Pb) of 0.1 weight % or less of a total weight of the plasma display panel, or 1000 parts per million (PPM) or less.
When a total percentage of a lead component is 1000 PPM or less, a lead percentage versus the weight of the plasma display panel can be 1000 PPM or less.
Alternately, it is also possible to provide a percentage of the lead component of a specific constituent element of the plasma display panel, by 1000 PPM or less. For example, a lead percentage of the barrier rib, a lead percentage of the dielectric layer, or a lead percentage of the electrode versus each weight of the constituent elements (the barrier rib, the dielectric layer, and the electrode) can be 1000 PPM or less.
It is also possible to provide lead percentages of all constituent elements such as the barrier walls, dielectric layers, the electrodes and the phosphor layers versus the weight of the plasma display panel, by 1000 PPM or less. The reason why a total percentage of a lead component is set to 1000 PPM or less as above is that the lead component can have a bad influence on a human body.
As shown in
The electrode arrangement of
The unit frame may be divided into a predetermined number of subfields, for example, eight subfields (SF1, . . . , SF8), to realize a time-division gray level expression. Each of the subfields is divided into a reset period (not shown), address periods (A1, . . . , A8) and a sustain periods (S1, . . . , S8).
In each of the address periods (A1, . . . , A8), a display data signal is applied at an address electrode X, and a corresponding scan pulse is sequentially supplied to each of scan electrodes Y.
In each of the sustain periods (S1, . . . , S8), a sustain pulse is alternatively supplied to the scan electrode Y and the sustain electrode Z, and a sustain discharge is induced in the discharge cells where wall charges are formed in the address (A1, . . . , A8).
The luminance of the plasma display panel is proportional to the number of sustain discharging pulses within the sustain discharging period (S1, . . . , S8) in a unit frame. When one frame forming one image is expressed by 8 subfields and 256 gray levels, different number of sustain pulses can be sequentially assigned in rates of 1:2:4:8:16:32:64: and 128 in each subfield. In order to obtain a luminance of 133 gray levels, the discharge cells are addressed during the subfield 1, the subfield 3 and the subfield 8, and the sustain discharge is performed.
The number of sustain discharging in each of the allocated subfields can be dynamically decided depending on the weights of subfields based on an automatic power control (APC) step. That is,
It is possible to variously change the number of sustain discharge pulses assigned in each subfield in consideration of a gamma characteristic and a panel characteristic. For example, the gray level assigned in the subfield 4 can decrease from 8 to 6, and the gray level assigned in the subfield 6 can increases from 32 to 34.
Each of the subfields includes a reset period for initializing discharge cells in an entire screen, an address period for selecting discharge cells, and a sustain period for sustaining the discharge of the selected discharge cells.
As shown in
Each of two reset signals includes a setup period (SU1, SU2), and a setdown period (SD1, SD2). In the setup period (SU1, SU2), the setup signal that is gradually increasing as much as V1 or V2 is supplied to all scan electrode Y at the same time, thereby inducing a minute discharging in all the discharge cells. Accordingly, the wall discharges are generated. The voltages V1 and V2 of the two reset signals may be same or different. For example, the voltage V1 can be higher than the voltage V2.
In the setdown period (SD1, SD2), a setdown signal that is gradually falling from a positive voltage lower than a peak voltage of the setup signal is supplied to all the scan electrode Y at the same time, thereby inducing an erase discharge at all the discharge cells. Accordingly, unnecessary ones of the wall charges and space charges generated by a setup discharge are erased, thereby uniformly leaving the wall charges required for address discharge in discharge cells.
When the reset signal is supplied to the scan electrode Y only one time, wall charges for address discharge may be improperly left at all the discharge cells due to the instability of the plasma display panel. Accordingly, as like the driving signal in the present embodiment, the reset signal is supplied twice in order to set the wall charges at all the discharge cells to be proper for address discharge. Therefore, the generation of bright defect can be reduced by supplying the reset pulse twice.
It is desirable that the voltage levels V1 and V2 for the reset signal rising during the setup period (SU, SU2) are about 160V to 250V. It is more desirable that the voltage levels V1 and V2 are about 190V to 250V. When the rising voltages V1 and V2 have the above voltage range, the bright defect generation can be reduced within a range greatly increasing a power consumption, and the flicker phenomena can be improved.
The driving signals shown in
It is desirable that the reset pulse is supplied to a scan electrode Y twice in the first subfield among a plurality of subfields for division-driving the frame as shown in
As shown in
Although the safe signal having a gradually increasing voltage value is shown in
As shown in
The maximum voltage of a reset signal can vary depending on a temperature. For example, a reset voltage at a high temperature or a low temperature can be set to be higher than a reset voltage at a normal temperature. The temperature can be driving temperature of panel and be measured temperature sensor positioned around the panel.
The high temperature can be a value more than 40° C., the low temperature can be a value less than 20° C. And, the normal temperature can be a value between 20° C. and 40° C.
It is desirable that a safe signal (SAFE) is supplied in one or two subfields among a plurality of subfields divided for driving one frame. Also, local flickering phenomenon can be reduced by supplying a safe signal SAFE in less than two subfields.
It is desirable that a rising voltage V3 of the safe signal SAFE is about 160 V to 210 V. When the rising voltage V3 is in the above range, the bright defect generation can be reduced within a range that greatly increases the power consumption, and the flickering phenomenon can be improved.
It is desirable that the number of subfields where the safe signal (SAFE) is supplied among a plurality of subfields is about one to three. In the address period, a negative scan signal is supplied to the scan electrodes Y, sequentially, and a positive data signal is supplied to the address electrodes X at the same time. When the voltage difference between the scan signal and the data signal and the wall voltage generated during the setup period are added, address discharge is induced in cells where the data signal is supplied. The address discharge induces a wall charge in the cells selected by the address discharge. The address discharge can be stably induced because the safe signal (SAFE) induces a negative wall charge at the scan electrode Y formed at all discharge cells. Accordingly, flickering phenomenon and bright defect generation can be prevented.
It is desirable to supply a bias voltage Vzb to a sustain electrode during the address period. Also, it is desirable that the bias voltage Vzb is about 140V to 190V. When the bias voltage Vzb is in the above range, the flickering phenomenon is not generated, and the luminance is improved.
It is desirable that the voltage of the scan signal is about −130V to −90V. When the scan signal is in the above voltage range, the flickering phenomenon and the bright defect are not generated. Also, a black luminance of a displayed image is improved.
The scan signals can be different in width in at least one of subfields. For example, the width of a scan signal in a following subfield can be narrower than the width of a scan signal in an advanced subfield in a time domain. The width of the scan signal can gradually falling depending on an order of arranging the subfields, for example, 2.6 us, 2.3 us, 2.1 us, . . . , 1.9 us or 2.6 us, 2.3 us, 2.3 us, 2.1 us, . . . , 1.9 us, and 1.9 us.
The width of scan signal is reduced as the location of subfields goes to the back. Then, the width of scan signal can increase again after a predetermined subfield.
In the sustain period, a sustain discharge is induced as a surface discharge type between a scan electrode (Y) and a sustain electrode (Z) by alternatively supplying a sustain pulse to a scan electrode and a sustain electrode.
In
Polarities and voltage levels of the driving signals shown in
As shown in
The electrode lines 202a, 202b, 203a and 203b cross the discharge cells and extend in one direction of the plasma display panel. As described above, a same driving pulse is supplied to discharge cells on the same electrode line. According to the first embodiment, the electrode lines are narrowed in width to improve an aperture ratio. Also, a plurality of electrode lines 202a, 202b, 203a and 203b are used to improve a discharge diffusion efficiency. It is desirable that the number of the electrode lines is decided in consideration of the aperture ratio.
It is desirable that the protrusion electrodes 202c and 203c are connected to electrode lines 202a and 203a closest to the center of a discharge cell within one discharge cell, and protrude in the direction of the center of the discharge cell. The protrusion electrodes 202c and 203c reduce a discharge initiation voltage when the plasma display panel is driven. By a distance between electrode lines 202a and 203a, the discharge initiation voltage increases and therefore, each of the electrode lines 202a and 203a has the protrusion electrode 202c or 203c connecting thereto in the first exemplary embodiment of the present invention. Since a discharge is initiated owing to even a low discharge initiation voltage between the closely formed protrusion electrodes 202c and 203c, the discharge initiation voltage of a plasma display panel can be reduced. The discharge initiation voltage refers a voltage level where the discharge is initiated when a pulse is supplied to at least one of the sustain electrodes 202 and 203.
Since the protrusion electrodes are a very small size, a width (W1) of a protrusion electrode portion connecting with the electrode line 202a or 203a may be substantially greater than a width (W2) of the protrusion electrode end portion by a manufacture tolerance. It is also possible to provide the width of the protrusion electrode end portion greater according to need.
The bridge electrodes 202d and 203d connect electrode lines of each sustain electrode. That is, the first bridge electrode 202d connects the electrode lines 202a and 202b of the first sustain electrode 202 each other. The second bridge electrode 203d connects the electrode lines 203a and 203b of the second sustain electrode 203 each other. The bridge electrodes 202d and 203d help a discharge initiated through the protrusion electrode to easily diffuse to electrode lines 202b and 203b which are distant away from the center of the discharge cell.
As described above, the electrode structure according to the first embodiment can suggest the number of the electrode lines, thereby improving the aperture ratio. The electrode structure according to the first embodiment also includes the protrusion electrodes, thereby reducing the discharge initiation voltage. Furthermore, the electrode structure according to the first embodiment can improve the electric discharge diffusion efficiency by the electrode lines distant away from the center of the discharge cell. In overall, the electrode structure according to the first embodiment improves the luminous efficiency of a plasma display panel.
The electrode lines 402a, 402b, and 403a, 403b cross the discharge cells, and extend in one direction of the plasma display panel. The electrode lines according to the second embodiment are formed to be narrower in width for improving an aperture ratio. It is desirable that the electrode lines have the width (W1) of about 20 μm and 70 μm for improving the aperture ratio and for smoothly inducing discharging at the same time.
As shown in
The first protrusion electrodes 402c and 403c are connected to the electrode lines 402a and 403a close to the center of the discharge cell within one discharge cell. The first protrusion electrodes 402c and 403c protrude in the center direction of the discharge cell. It is desirable that the first protrusion electrode is formed at the center of the electrode lines 402a and 403a. By forming the first protrusion electrodes 402c and 403c at the center of the electrode lines correspondingly to each other, the discharge initiation voltage of the plasma display panel can be more effectively lowered.
The bridge electrodes 402d and 403d are connected to electrode lines of each of the sustain electrode. The bridge electrodes 402d and 403d help the discharge initiated by the protrusion electrode to easily diffuse to the electrode lines 402b and 403b distant away from the center of the discharge cell. The bridge electrode 402d and 403d are placed within the discharge cell. However, the bridge electrodes can be also formed on a barrier rib 412 partitioning the discharge cells according to need.
The second protrusion electrodes 402e and 403e are connected to the electrode lines 402b and 403b distant away from the center of the discharge cell within one discharge cell. The second protrusion electrodes 402e and 403e protrude in an opposite direction from the center of the discharge cell. Accordingly, in the sustain electrode structure of the plasma display panel according to the second embodiment, the discharge can be diffused even to a space between the electrode lines 402b and 403b and the barrier ribs 413. Thus, the discharge diffusion efficiency can increase, thereby improving the light emission efficiency of the plasma display panel.
The second protrusion electrodes 402e and 403e can extend to the barrier ribs 412 partitioning the discharge cells. If the aperture ratio can be sufficiently compensated from other portion, it is possible to further extend a portion of the second protrusion electrodes 402e and 403e over the barrier ribs 412 in order to more improve the discharge diffusion efficiency. In the sustain electrode structure according to the second embodiment, it is desirable that the second protrusion electrodes 402e and 403e are formed on the center of the electrode lines 402b and 403b, thereby uniformly diffusing the discharge to the peripheral part of the discharge cell.
As shown in
By forming the two first protrusion electrodes at the sustain electrodes, the size of the sustain electrode at the center of the discharge cell is widened. Accordingly, space charges are sufficiently formed within the discharge cell before the discharge is initiated. Thus, the discharge initiation voltage is further lowered and a discharging speed is fastened. Furthermore, the amount of wall charge increases after the discharge is initiated. Therefore, the luminance thereof is improved, and the discharge is uniformly diffused throughout the entire discharge cells.
As shown in
The first protrusion electrodes 702c and 703c are connected to the electrode lines 402a and 403a close to the center of a discharge cell in one discharge cell, and protruding in a direction to the center of the discharge cell. It is desirable that one of the first protrusion electrodes is formed at a center of electrode line, and other two first protrusion electrodes are formed in symmetry with each other on the basis of a middle of the electric line. By forming three protrusion electrodes at each of the sustain electrodes, the discharge initiation voltage can be further lowered, and the discharging speed is more fastened compared to those in
As the number of the first protrusion electrodes increases as above, the size of sustain electrode at the center of a discharge cell is widened, the discharge initiation voltage is lowered, and the luminance thereof improved. On the contrary, it should be considered that the strongest discharge is induced and the brightest discharge light is emitted at the center of the discharge cell. That is, it is desirable that the number of the first protrusion electrodes is optimally selected and the sustain electrode structure is designed, considering, together with the discharge initiation voltage and the luminance efficiency, that the light emitted from the center of the discharge cell is much blocked and remarkably reduced as the number of the first protrusion electrodes increases.
Intervals (c1, c2 and c3) between the four electrode lines constituting each of the sustain electrodes can be equal to or different from each other. Widths (d1, d2, d3 and d4) of the electrode lines can be equal to or different from each other.
Bridge electrodes 1020, 1030, 1040, 1050, 1060, and 1070 connect corresponding two electrode lines, respectively. The bridge electrodes 1020, 1030, 1040, 1050, 1060, and 1070 make an initiated discharge to easily diffuse to the electrode line distant away from a center of the discharge cell. As shown in
As shown in
As described above, the transparent electrode formed of ITO can be eliminated from the plasma display panel of the plasma display apparatus according to the present invention. Thus, a manufacturing cost of the plasma display panel can be reduced. The plasma display panel according to the present invention includes the protrusion electrodes protruding from the scan electrode or the sustain electrode line in the direction of the center of the discharge or in the opposite direction thereof. Accordingly, the discharge initiation voltage can be reduced and the discharge diffusion efficiency can be enhanced. Furthermore, the gradually rising safe signal is supplied after supplying the reset signal twice in the plasma display panel according to the present invention. Therefore, flickering phenomenon and bright defect generation are reduced, thereby improving an image quality.
The foregoing exemplary embodiments and aspects of the invention 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. Also, the description of the exemplary embodiments of the present invention is intended to be illustrative, and not to limit the scope of the claims, and many alternatives, modifications, and variations will be apparent to those skilled in the art.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2006-0053145 | Jun 2006 | KR | national |
