This application claims priority based on an application entitled PLASMA DISPLAY PANEL INCLUDING SUSTAIN ELECTRODES HAVING DOUBLE GAP AND METHOD OF MANUFACTURING THE SAME, filed in the Korean Intellectual Property Office on Dec. 31, 2002, and assigned Serial No. 2002-87946, and on an application entitled PLASMA DISPLAY PANEL INCLUDING SUSTAIN ELECTRODES HAVING DOUBLE GAP AND METHOD OF MANUFACTURING THE SAME, filed in the Korean Intellectual Property Office on Jul. 25, 2003, and assigned Serial No. 2003-51631, the contents of which are hereby incorporated by reference.
1. Technical Field
The present invention relates to a flat panel display apparatus, and more particularly, to a plasma display panel (PDP) including sustain electrodes having a double gap and a method of manufacturing the panel.
2. Related Art
A PDP is a display apparatus using a gas discharge. A PDP is more suitable to a large size display than other flat panel displays such as a liquid crystal display (LCD), a field emission display (FED), and an electroluminescent display (ELD).
A large size PDP can be manufactured because it has a structure, in which a front glass substrate having a discharge electrode is separated from a rear glass substrate having a fluorescent material by a micro gap of 0.1–0.2 mm and plasma is formed therebetween, so that it operates as long as the gap between the front and rear glass substrates is exactly maintained.
PDPs are divided into a direct current (DC) type and an alternating current (AC) type. In the DC type, an electrode is directly exposed to a discharge gas, so the electrode sputters and evaporates with discharge repetitions. The AC type overcomes these problems of the DC type. In order to prevent an electrode from evaporating during a discharge, the AC type includes a dielectric layer covering the electrode. In addition, in order to prevent a fluorescent material from being damaged by ions generated during a discharge, the AC type includes electrodes, which are arranged in a horizontal direction. When starting a discharge using these electrodes, ions generated during the discharge are prevented from being injected into the fluorescent material, and only ultraviolet rays generated during the discharge are radiated onto the fluorescent material.
A plurality of address electrodes 22 used for writing data are disposed on the rear glass substrate 12. The address electrodes 22 are arranged in parallel with one another and are perpendicular to the first and second sustain electrodes 14a and 14b. Three address electrodes 22 are provided for each pixel. In a single pixel, three address electrodes 22 correspond to a red fluorescent material, a green fluorescent material, and a blue fluorescent material, respectively. The address electrodes 22 are covered with a second dielectric layer 24. A plurality of barrier ribs are disposed on the second dielectric layer 24, which is provided for light reflection. The plurality of barrier ribs 26 are spaced apart by a predetermined gap and parallel with the address electrodes 22. Each barrier rib 26 is disposed on the second dielectric layer 24 between adjacent address electrodes 22. In other words, the address electrodes 22 are alternately arranged with the barrier ribs 26. The barrier ribs 26 become in close contact with the protective layer 20 provided on the rear side of the front glass substrate 10 when the front and rear glass substrates 10 and 12 are joined together. Fluorescent materials 28a, 28b, and 28c are deposited in gaps between the barrier ribs 26 and excited by ultraviolet rays. The first fluorescent material 28a emits red (R) light, the second fluorescent material 28b emits green (G) light, and the third fluorescent material 28c emits blue (B) light.
After sealing the front glass substrate 10 to the rear glass substrate 12, unnecessary gas is evacuated from a gap therebetween, and then a plasma forming gas is injected into the gap. Although a single gas (for example, neon (Ne)) can be used as the plasma forming gas, a mixed gas (for example, Ne+Xe) is widely used.
In this conventional PDP, a pressure of the plasma forming gas (a partial pressure of a particular gas in a case of a mixed gas) needs to be maintained at a high level in order to avoid an increase in a sputter rate (SR) on the surface of the protective layer 20, and thus a high discharge voltage is required.
More specifically, referring to paschen curves G1 and G2 shown in
However, when the pressure P of a plasma forming gas is lowered, an SR on the surface of the protective layer 20 rapidly increases according to Formula (1), which defines the SR.
SR=(j/P)2.5 (1)
Where, “j” is an electric current density of the surfaces of the sustain electrodes 14a and 14b.
For this reason, in the conventional PDP, the pressures of a plasma forming gas must be maintained at a high level (e.g., 300–500 torr), and thus a discharge voltage is also high.
The present invention provides a plasma display panel (PDP) having a lowered discharge voltage and a maintained efficiency.
The present invention also provides a method of manufacturing the PDP.
According to an aspect of the present invention, there is provided a PDP including a front panel on which an image is displayed, the front panel comprising a plurality of sustain electrodes, a plurality of bus electrodes, a first dielectric layer covering both the plurality of sustain electrodes and the bus electrodes, and a protective layer; a rear panel separated from the front panel and hermetically sealed to the front panel, the rear panel comprising a plurality of data lines, a second dielectric layer covering the plurality of data lines, a plurality of barrier ribs, and a fluorescent layer; and a plasma forming gas arranged between the front and rear panels. A first sustain electrode selected from the plurality of sustain electrodes and a second sustain electrode facing the first sustain electrode have a double gap, thereby allowing a discharge voltage to be decreased without reducing discharge efficiency, and allowing a discharge to be started at a low voltage, and allowing the low voltage discharge to stop after the start of the sustaining discharge.
Preferably, the first sustain electrode comprises a first main electrode used to sustain a discharge after the discharge is started, and a first auxiliary electrode connected to the first main electrode and used to start the discharge. The first auxiliary electrode is a resistance element having a resistance of at least 30 Ω. Preferably, the second sustain electrode comprise a second main electrode used to sustain a discharge after the low voltage discharge is started, and a second auxiliary electrode connected to the second main electrode and used to start the low voltage discharge. The second auxiliary electrode is a resistance element having a resistance of at least 30 Ω.
Preferably, a first groove, in which the first auxiliary electrode is disposed, is formed in the first main electrode, and a second groove, in which the second auxiliary electrode is disposed, is formed in the second main electrode.
Preferably, at least one of the first and second grooves is near one of the plurality of barrier ribs.
Preferably, an entrance of at least one of the first and second grooves is narrower than the inside thereof.
Preferably, the first auxiliary electrode comprises a body disposed within the first groove, and an end portion extending from the body and disposed between the first and second sustain electrodes. Preferably, the second auxiliary electrode has the same structure as the first auxiliary electrode.
Preferably, the end portion of the first auxiliary electrode is parallel with or perpendicular to a bus electrode formed on the first sustain electrode to be parallel with the first sustain electrode or has a pointed shape. Preferably, the end portion of the second auxiliary electrode is parallel with or perpendicular to a bus electrode formed on the second sustain electrode to be parallel with the second sustain electrode or has a pointed shape.
Preferably, the first and second grooves are vertically or diagonally symmetrical.
Preferably, the first auxiliary electrode is a resistance element provided at an end of the first main electrode to face the second sustain electrode.
Preferably, the second auxiliary electrode is a resistance element provided at an end of the second main electrode to face the first sustain electrode.
Preferably, the first auxiliary electrode is a resistance element provided at an end of the first main electrode to face the second sustain electrode or the second auxiliary electrode.
Preferably, the plasma forming gas is a mixed gas of neon (Ne) and xenon (Xe) and contains 4–20 mole % Xe.
Preferably, the front panel further comprises a ditch formed above the first auxiliary electrode or the first and second auxiliary electrodes in the first dielectric layer. The first dielectric layer can comprise upper and lower dielectric layers having different dielectric constants, and the ditch is formed to expose the lower dielectric layer lying below the upper dielectric layer.
The first and/or second groove can be formed immediately above one of the plurality of barrier ribs.
According to another aspect of the present invention, there is provided a PDP including a front panel on which an image is displayed, the front panel comprising a plurality of sustain electrodes, a plurality of bus electrodes, a first dielectric layer covering the plurality of sustain electrodes and bus electrodes, and a protective layer; a rear panel separated from the front panel and hermetically sealed to the front panel, the rear panel comprising a plurality of data lines, a second dielectric layer covering the plurality of data lines, a plurality of barrier ribs, and a fluorescent layer; and a plasma forming gas arranged between the front and rear panels. At least one of the plurality of sustain electrodes comprises a main electrode used to sustain discharge, and an auxiliary electrode having a high resistance and used to start the discharge. The auxiliary electrode is connected to the main electrode such that at least part of the auxiliary electrode exists between two facing sustain electrodes.
Preferably, the auxiliary electrode is connected to an end of the main electrode such that the entire auxiliary electrode is disposed between the two facing sustain electrodes.
A ditch can be formed to a predetermined depth in the first dielectric layer immediately above the auxiliary electrode. The first dielectric layer can be formed by sequentially forming lower and upper dielectric layers having different dielectric constants, and the ditch is formed to expose the lower dielectric layer lying below the upper dielectric layer.
Preferably, a groove in which the auxiliary electrode is disposed is formed in the main electrode. The groove can be formed immediately above one of the plurality of barrier ribs.
According to still another aspect of the present invention, there is provided a method of manufacturing a PDP including a front panel having a front glass substrate, a plurality of sustain electrodes, a plurality of bus electrodes, and a first dielectric layer covering the plurality of sustain electrodes and bus electrodes, and a protective layer; a rear panel separated from the front panel and hermetically sealed to the front panel, the rear panel having a rear glass substrate, a plurality of data lines, a second dielectric layer covering the plurality of data lines, a plurality of barrier ribs, and a fluorescent layer; and a plasma forming gas arranged between the front and rear panels. The method comprises forming the sustain electrodes such that each sustain electrode faces another sustain electrode with a double gap allowing discharge to be started at a low voltage without decreasing discharge efficiency between the two facing sustain electrodes and allowing low-voltage discharge to stop after the start of the sustaining discharge.
Preferably, forming the sustain electrodes having the double gap therebetween comprises forming a transparent electrode material layer for forming the sustain electrodes on a surface of the front glass substrate, which faces the rear glass substrate panel, depositing a photoresist layer on the transparent electrode material layer, patterning the photoresist layer to have the same pattern as the sustain electrodes, thereby forming a photoresist layer pattern having a double gap, etching the transparent electrode material layer using the photoresist layer pattern as an etch mask, and removing the photoresist layer pattern.
Preferably, at least one of the two facing sustain electrodes is formed to comprise a main electrode used to sustain a discharge after the discharge is started, and an auxiliary electrode having a high resistance and used to start the low voltage discharge. The main and auxiliary electrodes can be integrally and simultaneously formed. Preferably, a groove is formed in the main electrode, and the auxiliary electrode is formed in the groove. Preferably, the auxiliary electrode is formed at an end of the main electrode such that the auxiliary electrode is disposed between the two facing sustain electrodes. Preferably, the auxiliary electrode comprises a body formed within the groove, and an end portion extended from the body out of the groove to be disposed between the two facing sustain electrodes. The body has a serpentine shape in a horizontal plane or a vertical plane. Preferably, the end portion is parallel with or perpendicular to bus electrodes formed on the two facing sustain electrodes, respectively, or has a pointed shape. Preferably, an entrance of the groove is narrower than the inside of the groove. Preferably, the auxiliary electrode is formed in each of the two facing sustain electrodes such that the auxiliary electrodes in the respective two facing sustain electrodes are vertically or diagonally symmetrical.
Preferably, the method further comprises forming a ditch in the first dielectric layer immediately above the double gap. The first dielectric layer can be formed by sequentially stacking a lower dielectric layer and an upper dielectric layer having different dielectric constants, and the ditch is formed to expose the lower dielectric layer lying below the upper dielectric layer.
The groove can be formed immediately above one of the plurality of barrier ribs.
According to the present invention, a pressure (partial pressure) of a plasma forming gas used in a PDP is maintained at a high level, like in the conventional PDP, and a discharge voltage is remarkably lowered as compared to that of the conventional PDP.
A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein:
Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. In the drawings, the thickness of layers and regions are exaggerated for clarity.
In
Referring to the first and second paschen curves G1 and G2, it can be inferred that when a plasma forming gas is a mixed gas, as well as when it is a single gas, a voltage when a product Pd of a pressure P of a plasma forming gas (hereinafter, referred to as a gas pressure P) and a gap “d” between sustain electrodes is 1 is a minimum discharge start voltage (Vf)min.
A discharge start voltage Vf is given by Formula (2).
Where B is a constant, and K is given by Formula (3).
Where γ is a secondary electron emission coefficient, which is determined in accordance with a material of the sustain electrodes.
A minimum Pd value Pdmin and the minimum discharge start voltage (Vf)min are given by Formulae (4) and (5), respectively.
Where “e” is a natural logarithm, and A is a constant.
Generally, the condition Pd=1 is satisfied by decreasing the gap “d” between sustain electrodes and increasing the gas pressure P or by increasing the gap “d” and decreasing the gas pressure P.
When decreasing the gap “d” between sustain electrodes and increasing the gas pressure P, a sputter rate (SR) at the surface of a protective layer (e.g., a MgO layer) can be decreased according to Formula (1) because the gas pressure P is high, but brightness or efficiency is rapidly decreased due to a decrease in the gap “d” between sustain electrodes.
Conversely, when increasing the gap “d” and decreasing the gas pressure P, the problem occurring in the above situation can be overcome because the gap “d” between sustain electrode is wide, but the SR at the surface of the protective layer rapidly increases because the gas pressure P is low.
Accordingly, in conventional PDPs, the gas pressure P is set high and the gap “d” between sustain electrodes is set to a proper value, which prevents brightness or efficiency from excessively decreasing, in order to lower the SR at the surface of a protective layer. As a result, the PD value exceeds 1. For example, the PD value becomes 3 through 4. However, when the PD value exceeds 1, a discharge start voltage is greater than the minimum discharge start voltage (Vf)min, as shown in
Accordingly, in order to lower the SR at the surface of a protective layer, the present invention provides a PDP including a sustain electrode for alleviating the problem, which occurs when the gap “d” between sustain electrodes decreases, by increasing the gas pressure P and decreasing the gap “d” between sustain electrodes and for maintaining the Pd value close to 1.
Since a PDP according to the present invention is characterized by a sustain electrode, the following description of the invention concentrates on a sustain electrode, and variously modified sustain electrodes, which can accomplish the objectives of the present invention.
A sustain electrode used in a PDP according to a first embodiment of the present invention will be described in detail with reference to
In
The structure and details of the second resistance element formed in the second groove 50 are the same as those of the first resistance element, and thus detailed description thereof will be omitted.
Like the first resistance element, the second resistance element is composed of a body 54a and an end portion 54b. The end portion 54b of the second resistance element is positioned between the first and second sustain electrodes 40 and 42 and is parallel with the end portion 52b of the first resistance element. As shown in
As described above, since the gap g3 between the first and second resistance elements is less than the gap g2 between the first and second sustain electrodes 40 and 42, a discharge start voltage in a PDP according to the present invention is lowered compared to the conventional PDP. Since the first and second resistance elements have much greater resistance than the first and second sustain electrodes 40 and 42, immediately after the start of a discharge, current is supplied mostly through the first and second sustain electrodes 40 and 42 except for the first and second resistance element. As a result, a discharge having started between the first and second resistance element is spread between the first and second sustain electrodes 40 and 42. The discharge spread between the first and second sustain electrodes 40 and 42 is sustained at the same voltage as the discharge start voltage. When wall charges are used, a sustain voltage can be sustained lower than the discharge start voltage.
Simulations of the following two cases were carried out in order to prove the theory that a discharge start voltage decreases when a PDP is provided with the first and second sustain electrodes 40 and 42 shown in
It is preferable that the percentage of Xe in the mixed gas of Ne and Xe is 4–22 mole % in a PDP according to embodiments of the present invention.
The following description concerns sustain electrodes, which are used in a PDP having the above-described characteristics according to second through ninth embodiments of the present invention.
While the sustain electrodes 40 and 42 in a PDP according to the first embodiment of the present invention are illustrated in three dimensions in
In
Referring to
In comparison of
More specifically, the end portion 60b of the third resistance element is parallel with the end portion 62b of the fourth resistance element between the first and second sustain electrodes 40 and 42. However, the end portions 60b and 62b are parallel with each other in a direction perpendicular to the end portions 52b and 54b of the respective first and second resistance elements so that the end portions 60b and 62b are parallel with the sides of the first and second grooves 48 and 50. In addition, the end portion 60b of the third resistance element is positioned on one side of the first groove 48, and the end portion 62b of the fourth resistance element is positioned on the other side of the first groove 48, so that the end portions 60b and 62b face each other. The end portions 60b and 62b have a predetermined length, which is preferably less than the gap g2 between the first and second sustain electrodes 40 and 42. In addition, it is preferable that the end portion 60b of the third resistance element is possibly close to the second sustain electrode 42. For example, the end portion 60b of the third resistance element has a length of 20 μm through a length less than the gap g2 between the first and second sustain electrodes 40 and 42. It is also preferable that the end portion 62b of the fourth resistance element is possibly close to the first sustain electrode 40. It is more preferable that a horizontal gap between the end portions 60b and 62b is less than the gap g2 between the first and second sustain electrodes 40 and 42.
Referring to
Likely the first through fourth resistance elements, the fifth resistance element is simultaneously formed while the first groove 48 is formed in the first sustain electrode 40, so the body 64, the horizontal part 64c, and the protrusion 64b are integrally formed. However, for clarity; these are distinguishably illustrated in
The end portions of the respective fifth and sixth resistance elements are vertically symmetric. A horizontal part 66c of the sixth resistance element corresponds to the horizontal part 64c of the fifth resistance element, and a protrusion 66b corresponds to the protrusion 64b. A predetermined gap g4 exists between the protrusions 64b and 66b. It is preferable that the gap g4 between the protrusions 64b and 66b is less than the gap g2 between the first and second sustain electrodes 40 and 42. For example, the gap g4 is preferably about 20 μm and appropriately about 40 μm.
Referring to
More specifically, in
Referring to
More specifically, the third sustain electrode 90 is composed of a body 90a and protrusion 90b in an upside down T shape. The body 90a has a predetermined width w1 between the first and second barrier ribs 80 and 82 so that an enough space to form a resistance element therewithin exists between the body 90a and each of the first and second barrier ribs 80 and 82. The protrusion 90b is extended from an end of the body 90a facing the fourth sustain electrode 92 in opposite directions to be parallel with the first bus electrode 44. The protrusion 90b is separated from each or the first and second barrier ribs 80 and 82 by a predetermined gap w2, which is less than a gap w3 between the body and each of the first and second barrier ribs 80 and 82. The fourth sustain electrode 92 is formed to face the third sustain electrode 90. The predetermined gap g2 exists between the third and fourth sustain electrodes 90 and 92. The fourth sustain electrode 92 is composed of a body 92a and protrusion 92b in a T shape. The third and fourth sustain electrodes 90 and 92 are vertically symmetric. Accordingly, a width of the body 92a of the fourth sustain electrode 92 is the same as the width w1 of the body 90a of the third sustain electrode 90. A gap between the body 92 and each of the first and second barrier ribs 80 and 82 is the same as the gap w3 between the body 90a and each of the first and second barrier ribs 80 and 82. In addition, a gap between the protrusion 92b of the fourth sustain electrode 92 and each of the first and second barrier ribs 80 and 82 is the same as the gap w2 between the protrusion 90b of the third sustain electrode 90 and each of the first and second barrier ribs 80 and 82. An eleventh resistance element 94 is composed of a body 94a and an end portion 94b and is integrally formed with the third sustain electrode 90 between the third sustain electrode 90 and the first barrier rib 80. A twelfth resistance element 96 is composed of a body 96a and an end portion 96b and is integrally formed with the fourth sustain electrode 92 between the fourth sustain electrode 92 and the first barrier rib 80. The eleventh resistance element 94 can be disposed between the third sustain electrode 90 and the second barrier rib 82. The twelfth resistance element 96 can be disposed between the fourth sustain electrode 92 and the second barrier rib 82. The body 94a of the eleventh resistance element 94 is disposed between the body 90a of the third sustain electrode 90 and the first barrier rib 80. The end portion 94b of the eleventh resistance element 94 is extended from the body 94a, runs through a space between the first barrier rib 80 and the protrusion 90b of the third sustain electrode 90 and is extended between the third and fourth sustain electrodes 90 and 92. The end portion 94b is parallel with the protrusion 90b of the third sustain electrode 90. The eleventh and twelfth resistance elements 94 and 96 are vertically symmetric. Accordingly, the end portion 96b of the twelfth resistance element 96 is parallel with the end portion 94b of the eleventh resistance element 94 between the third and fourth sustain electrodes 90 and 92. As a result, the gap g4 between the end portion 94b of the eleventh resistance element and the end portion 96b of the twelfth resistance element is less than the gap g2 between the third and fourth sustain electrodes.
Referring to
Referring to
More specifically, a third groove 110a is formed at the center of the fifth sustain electrode 110, and a fourth groove 112a is formed at the center of the sixth sustain electrode 112. Entrances 110b and 112b of the respective third and fourth grooves 110a and 112a are narrower than the third and fourth grooves 110a and 112a. The fifteenth and sixteenth resistance elements 114 and 116 exist in the third and fourth grooves 110a and 112a, respectively. The fifteenth resistance element 114 is composed of a body 114a and an end portion 114b extending out of the third groove 110a. The sixteenth resistance element 116 is composed of a body 116a and an end portion 116b extending out of the fourth groove 112a. The end portions 114b and 116b are parallel with each other between the fifth and sixth sustain electrodes 110 and 112 and also parallel with the fifth and sixth sustain electrodes 110 and 112. Since the end portions 114b and 116b exist between the fifth and sixth sustain electrodes 110 and 112, which are separated by the same gap as the gap g2 between the first and second sustain electrodes 40 and 42, a gap g6 between the end portions 114b and 116b is less than the gap g2 between the fifth and sixth sustain electrodes 110 and 112.
Referring to
In the above-described embodiments, it is preferable that a gap between a main electrode and an auxiliary electrode is 15 μm or less.
The shapes of various sustain electrodes described above in the embodiments of the present invention are different, but the sustain electrodes can be represented by an equivalent circuit, as shown in
Referring to
The currents I1 and I2 shown in
Accordingly, when appropriate values are given to the first and second resistances R1 and R2, the currents I1 and I2 flowing across the first and second resistances R1 and R2, respectively, can be obtained using Formulae (6) and (7).
For example, when the first resistance R1 is 1 kΩ and the second resistance R2 is 30 Ω, the current I1 flowing across the first resistance R1 is [30/(1000+30)]It according to Formula (6), and the current I2 flowing across the second resistance R2 is [1000/(1000+30)]It according to Formula (7). Consequently, a ratio of the current I1 flowing across the first resistance R1 to the current I2 flowing across the second resistance R2 is 3:100. The inference can be made from this fact that the current I1 flowing across the first resistance R1, which is much greater than the second resistance R2, is much less than the current I2 flowing across the second resistance R2.
This result is applied to the present invention, as it is. In other words, since the resistance of the various resistance elements is much greater than the resistance of the first through eighth sustain electrodes, current flowing across the various resistance elements is much less than current flowing across the first through eighth sustain electrodes.
Accordingly, after a discharge is started at a low voltage using the resistance elements, the flow of current is extremely restricted in the resistance elements, and most current flows through sustain electrodes, which have much less resistance than the resistance elements.
It has been described that resistance elements are provided in the first through eighth sustain electrodes, respectively. However, when considering the functions of the first through eighth sustain electrodes and the resistance elements, the first through eighth sustain electrodes can be regarded as first through eighth main electrodes, and the first through eighteenth resistance elements can be regarded as first through eighteenth auxiliary electrodes. In this situation, a sustain electrode according to the present invention is composed of a main electrode and an auxiliary electrode.
The following description concerns a PDP according to a tenth embodiment of the present invention. The PDP according to the tenth embodiment is different from the PDPs according to the first through ninth embodiments in that a ditch is formed on an upper plate of the PDP.
Referring to
A dielectric layer 168 is formed to a predetermined thickness on the front glass substrate 10 so that the ninth and tenth sustain electrodes 160 and 162, the third and fourth bus electrodes 164 and 166, and the nineteenth and twentieth resistance elements 160a and 162a are covered with the dielectric layer 168. Preferably, the dielectric layer 168 transmits incident light. A first ditch GR1 is formed to a predetermined depth in the dielectric layer 168. Preferably, the first ditch GR1 is formed immediately above the nineteenth and twentieth resistance elements 160a and 162a. It is preferable that the first ditch GR1 is formed as deep as possible but it does not expose the nineteenth and twentieth resistance elements 160a and 162a. In other words, it is preferable that a gap between the bottom of the first ditch GR1 and the nineteenth and twentieth resistance elements 160a and 162a is minimized.
When the first ditch GR1 is formed in the dielectric layer 168, a discharge gas can exist in the first ditch GR1. Accordingly, a gap between the discharge gas and the nineteenth and twentieth resistance elements 160a and 162a is narrowed so that a discharge voltage is decreased compared to when the first ditch GR1 is not formed in the dielectric layer 168. In other words, since a gas in the first ditch GR1 has a lower dielectric constant than the dielectric layer 168, the intensity of an electric field in the first ditch GR1 is greater than other portions. Accordingly, discharge can be started with a lower discharge voltage in the first ditch GR1 than in the other portions. Since a pressure within the PDP and the discharge gas do not change, light emission efficiency does not decrease.
A protective layer 170 (made of MgO) is formed on the dielectric layer 168 to cover the surface of the first ditch GR1.
The dielectric layer 168 preferably includes a single layer but can include multiple layers. For example, as shown in
To prove the superiority of a PDP according to the present invention to a conventional PDP, experiments were performed, and the results of the experiments are illustrated in
In the experiments, the PDP (hereinafter, referred to as a first PDP) according to the eighth embodiment of the present invention shown in
To compare the characteristics of the first through third PDPs, the sustain voltage-efficiency characteristics (hereinafter, referred to as first characteristics) and the sustain voltage-brightness characteristics (hereinafter, referred to as second characteristics) of the first through third PDPs were measured.
In
Referring to
In the meantime, to measure the first characteristics of the first and third PDPs in a stable discharge state, a sustain voltage was maintained at 205 V higher than the discharge start voltage by about 10 V in the third PDP while an efficiency (lm/W) of the third PDP was measured, and the Xe ratio was raised to 12% in the first PDP and then the efficiency of the first PDP was measured at a sustain voltage of 202.5 V. The efficiency of the third PDP was 1.210 lm/W while the efficiency of the first PDP was 1.722 lm/W at the Xe ratio of 12%. In other words, the efficiency of the first PDP was about 42% higher than that of the third PDP.
Referring to
It can be inferred from the results shown in
The following description concerns the results of measuring the first and second characteristics of the second and third PDPS. In measuring experiments, inner conditions such as a type of discharge gas, a discharge gas mixture ratio, an inner pressure, a duty ratio, and a type of fluorescent layer were the same in the second and third PDPs.
In
Referring to
Referring to
As described above, when the second characteristics of the second and third PDPs are considered synthetically, it can be concluded that the second characteristic of the second PDP is superior to that of the third PDP.
The following description concerns consumption power of the PDP having a ditch in an upper dielectric layer according to the tenth embodiment of the present invention and consumption power of the third PDP.
In
Referring to
More specifically,
Referring to
Before the start of discharge, the second through fifth capacitances exist in the upper plate of the fourth PDP, as shown in
Referring to
Since a displacement current is proportional to a capacitance, before the start of discharge, a displacement current induced between the first and second electrodes E1 and E2 in the fourth PDP is less than that induced between the first and second sustain electrodes 14a and 14b in the third PDP.
Consumption power W proportional to a displacement current fCV is expressed by Formula (9).
W=fCV2 (9)
Here, “f” denotes an alternating current (AC) voltage frequency, C denotes a capacitance, and V denotes an AC voltage.
As described above, a capacitance or displacement current fCV of a parasitic capacitor in the fourth PDP is less than that of a parasitic capacitor in the third PDP. Accordingly, it can be inferred from Formula (9) that the consumption power of the fourth PDP is less than that of third PDP.
A first simulation was performed to inspect changes in a discharge start voltage according to existence or non-existence of a resistance element as an auxiliary electrode in a sustain electrode. A second simulation was performed to inspect the relationship between a ditch formed in an upper dielectric layer and a discharge start voltage.
In the first simulation, a first simulated PDP shown in
In
The second simulated PDP shown in
In the first simulation, the thickness of the upper and lower dielectric layers 190 and 192 was 30 μm, and a dielectric material having a dielectric constant of 12 was used in the first and second simulated PDPs shown in
Table 1 shows the results of measuring a discharge start voltage in the first and second simulated PDPs.
Referring to Table 1, the discharge start voltage is lower in the second simulated PD than in the first simulated PDP regardless of the Xe ratio. This result means that when a sustain electrode includes a resistance element according to the present invention, discharge can be started at a lower voltage than in the conventional PDP. It also means that when the discharge start voltage of the second simulated PDP is the same as that of the first simulated PDP, the Xe ratio in the second simulated PDP can be increased to be higher than that in the first simulated PDP.
When the Xe ratio is increased, light emission efficiency is also increased. Accordingly, when the same discharge start voltage is used, the light emission efficiency of the second simulated PDP is higher than that of the first simulated PDP.
In the second simulation, a third simulated PDP shown in
As shown in
The fourth simulated PDP shown in
In the second simulation, the thickness of the upper and lower dielectric layers 190 and 912, a dielectric material, the width of the sustain electrodes 194, 196, 204, and 206, the width of pulses of a voltage applied to the sustain electrodes 194, 196, 204, and 206, a discharge gas, and a Xe ratio in the discharge gas were the same in the third and fourth simulated PDPs. The Xe ratio was increased from 5% to 10% and 30%, and a pressure was maintained at 505 torr.
Table 2 shows the results of measuring a discharge start voltage in the third and fourth simulated PDPs.
Referring to Table 2, the discharge start voltage is much lower in the fourth simulated PD than in the third simulated PDP. In particular, when Table 1 is compared Table 2, the discharge start voltage of the fourth simulated PDP is much lower than that of the second simulated PDP.
According to the results of the first and second simulations, it can be inferred that when two sustain electrodes include resistance elements, respectively, separated by a less distance than a distance between the two sustain electrodes, and a ditch is formed in a dielectric layer covering the sustain electrodes and the resistance elements in a PDP, a discharge start voltage is decreased compared to a PDP including a resistance element without a ditch according to the present invention as well as the conventional PDP.
Consequently, in the fourth simulated PDP, discharge can be started at a lower voltage than used in the third simulated PDP, and a Xe ratio in a discharge gas can be increased, thereby providing high light emission efficiency at a lower discharge start voltage.
The following description concerns a method of manufacturing a PDP according to an embodiment of the present invention, and more particularly, a method of manufacturing a sustain electrode used in a PDP. Here, the first through eighth sustain electrodes are referred to as main electrodes, and the resistance elements are referred to as auxiliary electrodes. In addition, the assumption is made that a sustain electrode includes a main electrode and an auxiliary electrode.
Referring to
More specifically, each sustain electrode includes a space, and one of the resistance elements shown in
The sustain electrodes having the above-described features can be acquired by reflecting these features on a process of patterning a photoresist layer deposited on the transparent electrode material layer. In other words, by reflecting these features of the sustain electrodes on a process of patterning the photoresist layer, a photoresist layer pattern having these features, i.e., the same shape of the sustain electrodes, is formed. Then, by etching the transparent electrode material layer using the photoresist layer pattern as an etch mask, the sustain electrodes having these features are formed on the glass substrate.
The sustain electrodes shown in one of
After forming the sustain electrodes on the glass substrate, bus electrodes are formed on the respective sustain electrodes to be parallel with the respective sustain electrodes in step 230. Black stripes (not shown) are formed between the sustain electrodes, and a dielectric layer (168 shown in
Succeeding processes such as a process of forming a protective layer on the dielectric layer 168 having the first or second ditch GR1 or GR2, a seal line printing process, and a process of forming a protective layer, processes for forming a rear glass substrate panel, a process of sealing the front glass substrate panel to the rear glass substrate panel, a process of injecting a plasma forming gas, and a packaging process are performed according to a typical procedure. However, it is preferable that the plasma forming gas is a mixed gas of Ne and Xe, which contains 4–20% Xe.
As described above, a sustain electrode used in a PDP according to the present invention includes a main electrode, through which most current flows after the start of a discharge, and an auxiliary electrode (i.e., a resistance element), which has a high resistance for a low voltage discharge. In addition, a ditch is formed immediately above the auxiliary electrode in a dielectric layer covering the main and auxiliary electrodes. A gap between auxiliary electrodes included in different sustain electrodes, respectively, is narrower than a gap between the main electrodes. Accordingly, a discharge start voltage can be decreased compared to conventional PDPs. In particular, application of a discharge voltage induces an intensive electric field in the ditch, which facilitates discharge of the discharge gas in the ditch. Accordingly, the discharge start voltage can be further lowered in a PDP including the ditch as well as the auxiliary electrode according to the present invention. Moreover, the gap between the main electrodes in a PDP according to the present invention is as wide as a gap between sustain electrodes in the conventional PDPs. Accordingly, degradation of brightness and efficiency can be prevented in a PDP according to the present invention while the discharge start voltage can be lowered by more than 20 V compare to the conventional PDPs.
While this invention has been particularly shown and described with reference to exemplary embodiments thereof, these embodiments should be considered in descriptive senses only and not for purposes of limitation. For example, those skilled in the art of the present invention can use auxiliary electrodes (i.e., resistance elements) having different shapes from those described in the above embodiments without departing from the spirit of the invention. For example, instead of providing an auxiliary electrode in a groove formed in a sustain electrode, resistance elements according to the present invention can be provided in the conventional sustain electrodes 14a and 14b, respectively, which do not have a groove, as shown in
Number | Date | Country | Kind |
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10-2002-0087946 | Dec 2002 | KR | national |
10-2003-0051631 | Jul 2003 | KR | national |
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