Alternating-current Plasma Display Panel Research Articles

Discharge instability in alternating-current display panels (AC-PDPs)

ABSTRACTIn this study, discharge properties of 50-in. alternating current plasma display panels (AC-PDPs) were investigated as functions of the gap of ITO electrodes, the height and width of the barrier rib, and the width of address electrodes. The effects of each component on the discharge instability were studied. The change in the discharge gap of ITO electrode mainly affected the discharge instability, and moving-discharge stain increased with increasing the ITO gap. The moving-discharge stain was strongly related to unexpected opposite (or plate-gap) discharge in the energy recovery(ER)-up period and the main reason was the increase of charge variation in the discharge cells. The discharge instability in the AC-PDPs was dramatically reduced by applying overlapped sustain waveform and ER-coil with a low inductance. Both of overlapped sustain waveform and ER-coil with a low inductance suppressed the opposite discharge during ER-up period, and these reduced the charge variations in the discharge cells. However, these caused an increase in the power consumption and led to a decrease in the discharge efficiency. Consequently, the unexpected opposite discharge during ER-up period is considered as the main reason for the discharge instability, and the low inductance of ER-coil and overlapped sustain waveform effectively suppress the opposite discharge in ER-up period.

Investigation for the effect of redeposited Mg particles on the discharge characteristics in an alternating-current plasma display panel

ABSTRACTIn this paper, the influences of the redeposited Mg particles in the boundary image sticking region on the electron emission of the MgO surface and related discharge characteristics of an alternating-current plasma display panel were examined by using the cathodoluminescence and intensified charge-coupled device techniques. The experimental results showed that the electron emission at the redeposited region of the Mg particles on the MgO surface was intensified and concentrated compared with those for nonredeposited region of the Mg particles, thereby resulting in extremely improving the discharge characteristics in the 42 in high definition (HD) alternating-current plasma display panels (ac-PDPs) with a He (35%)-Xe (11%)-Ne contents.

Influence of overlapped sustain waveform on panel-aging characteristics based on MgO surface morphology variation in alternating-current plasma display panel

ABSTRACTThis paper has been investigated the changes in the discharge characteristics and surface morphology of the MgO surface on both the indium thin oxide (ITO) and bus electrodes when the conventional (non-overlapped) and overlapped sustain waveforms are applied during the panel-aging process in alternating-current plasma display panel. For conventional sustain waveform, the strong surface discharge is confined within the ITO electrode, whereas for overlapped sustain waveform, the strong surface discharge is produced and spread toward the end of the bus electrode as well as the ITO electrode. It is demonstrated that the overlapped sustain waveform is a very effective aging waveform that can obtain the uniform surface morphology of the MgO thin film on both the ITO and bus electrodes.

Experimental study on permanent image sticking of single and double barrier ribs in alternating-current plasma display panel

ABSTRACTThe permanent image sticking phenomena were examined and compared for the two different barrier rib structures such as the single and double barrier ribs. To compare the permanent image sticking phenomena for both barrier rib structures, the differences in the display luminance, address discharge delay time, firing voltage, visible light profile, impulse, and SEM image of the image sticking cells during long time discharges were measured. The proposed double barrier structure showed that the variations in the surface states of the MgO layer remained almost the same between ITO and bus electrodes during long time discharges, thereby reducing the difference of the luminance and statistical address delay times. As a result, the double barrier rib structure was observed to mitigate the permanent image sticking in comparison with the single barrier rib structure in the 50 in full HD ac-PDPs with a He (35%)-Xe (11%)-Ne contents.

Defect states of transition metal-doped MgO for secondary electron emission of plasma display panel

High secondary electron emission (SEE) yield is one of the important properties of MgO for industrial applications such as alternating-current plasma display panel (AC-PDP), which reduces the firing voltage for discharge. SEE induced by low-energy Ne and Xe ions can be described by potential emission mechanism of Auger neutralization. Defect states in MgO can play an important role in enhancing the SEE. The electronic density of states of Ti-, Cr-, Fe-, Ni-, Zn-doped and undoped MgO was calculated using CASTEP. The occupied defect levels of the Ti-, Cr-, Fe-, Ni- and Zn-doped MgO are at 5.23, 3.90, 2.76, 1.22 and 0.06 eV above the valence band, respectively. Higher defect level appears to be advantageous for getting larger SEE yield. Considering the fact that Ti-doped MgO reveals n-type conductivity, Cr seems to be the proper dopant among the studied elements for the purpose of high SEE yield in AC-PDP.

The effects of total gas pressure and Xe partial pressure on the properties of plasma display panels with two-opposite-electrode cells

The effects of total pressure and Xe partial pressure on the characteristics of an alternating-current plasma display panel with a two-opposite-electrode discharge cell configuration and a three-electrode surface-discharge cell configuration were investigated in terms of the following electro-optical properties: breakdown voltage, sustain voltage, wall charge transfer curve, infrared emission characteristics, luminance and luminous efficacy. Despite the longer discharge gap length, the results of the experiment and three-dimensional plasma simulation indicated that the opposite-discharge configuration has a significantly lower breakdown voltage than the surface-discharge configuration. Furthermore, the ratio of the increase in the breakdown voltage for the opposite-discharge configuration to the incremental Xe partial pressure was found to be smaller than that of the surface-discharge configuration. Because of its low driving voltage and possible use of high-Xe partial pressure, the opposite-discharge mode exhibited a higher luminous efficacy compared with the surface-discharge mode. These results indicated that the two-opposite-electrode discharge cell configuration has a cost reduction potential in electronics as well as high efficacy for plasma displays.

Effect of C and H contamination on the MgO surface properties studied using the first-principles method

In the former experiment, the effect of aging temperature on the discharge characteristics of the magnesium oxide (MgO) film of the alternating-current plasma display panel was investigated from the point of view of surface contamination. It was found that C and H surface contamination can affect the surface properties, such as the surface conductivity and secondary electron emission (SEE) yield, of the MgO surface. For a better understanding of the effect of C and H contamination on the MgO surface properties, the electronic structures of C- and H-adsorbed MgO (100) surfaces were calculated through the first-principles method, using Cambridge Serial Total Energy Package. The occupied defect levels of the C-adsorbed MgO (100) surface, which lie in the mid-gap, play an important role in the potential emission mechanism of SEE. More C contamination at the MgO surface can induce more SEE and can thus reduce the firing voltage for discharge. The Fermi level of the H-adsorbed MgO (100) surface cuts the bottom edge of the conduction band, which means that the H-adsorbed MgO (100) surface reveals n-type conductivity. More H contamination at the MgO surface can reduce the wall charge accumulation ability and can thus increase the sustain voltage for discharge.

Influence of Al2O3 reflective layer under phosphor layer on luminance and luminous efficiency characteristics in alternating-current plasma display panel

This paper examines the optical and discharge characteristics of alternating-current plasma display panel when adopting the Al2O3 reflective layer. The Al2O3 reflective layer is deposited under the phosphor layer by using the screen-printing method. The resulting changes in the optical and discharge characteristics, including the power consumption, color temperature, luminance, luminous efficiency, scanning electron microscopy image, and reflectance, are then compared for both cases with and without Al2O3 reflective layer. As a result of optimizing the thicknesses between the Al2O3 and phosphor layers, the luminance and luminous efficiency are improved by about 17% and 7%, respectively.

Discharge characteristics of protective LaB6 thin films in an AC plasma display panel

Lanthanum hexaboride (LaB6) thin films were used as protective layers in alternating current plasma display panels (AC-PDPs). The firing voltages and discharge delay time of protective LaB6 thin films were evaluated and compared with the conventional protective MgO layers in planar-type test panels filled with 5%–15% Ne-Xe. By employing LaB6 thin films as protective layers, both the firing voltages and discharge delay time decreased drastically. Improvements in the discharge properties of the LaB6 thin film could be attributed to the lower work function, offering more priming electrons during the discharge process.

Influence of Ion Bombardment onto Phosphor Layer on Temporal Image Sticking in Alternating-Current Plasma Display Panel

Influence of Ion Bombardment onto Phosphor Layer on Temporal Image Sticking in Alternating-Current Plasma Display Panel

Influence of Ion Bombardment onto Phosphor Layer on Temporal Image Sticking in Alternating-Current Plasma Display Panel

We found that ion bombardment onto a phosphor layer during a sustained discharge was a key factor in inducing temporal image sticking of alternating-current (AC) plasma display panels (PDPs) through facilitated absorption of H2O onto the phosphor layer. We also found that ion bombardment onto the phosphor layer during the sustain discharge strongly depended on the bias conditions of the address electrode on which the phosphor layers were deposited. As a result, the positive-biased or floated address electrode condition could minimize the ion bombardment onto the phosphor layer during the sustain discharge, thus suppressing the absorption of H2O onto the phosphor layer, and ultimately preventing temporal image sticking.

Improvement in Discharge Delay Time by Accumulating Positive Wall Charges on Cathode MgO Protective Layer Surface in Alternating-Current Plasma Display Panels

The improvement in discharge delay time by accumulating positive wall charges on a cathode MgO protective layer surface in plasma display panels (PDPs) was investigated. The number of exoelectrons emitted from the cathode MgO surface, which trigger the discharge, increases with the accumulation of positive wall charges on the cathode MgO surface, thereby reducing both the statistical and formative delay times, ts and tf, respectively, of the address discharge. The correlations between exoelectron emission and ts and tf were investigated, revealing that the address discharge is triggered by multiple exoelectrons. In addition, it is found that exoelectron emission plays an important role in wall charge leakage during the address period. The present results confirmed that the accumulation of positive wall charges on the cathode MgO protective layer surface is effective for improving the discharge delay times ts and tf in not only PDPs but also common dielectric barrier discharge.

Improvement in Discharge Delay Time by Accumulating Positive Wall Charges on Cathode MgO Protective Layer Surface in Alternating-Current Plasma Display Panels

Improvement in Discharge Delay Time by Accumulating Positive Wall Charges on Cathode MgO Protective Layer Surface in Alternating-Current Plasma Display Panels

Spatiotemporal behavior of the excited Xe atom density in the 1s5 metastable state according to the hoof‐type electrode structure in an alternating‐current plasma display panel

To improve the luminescence characteristics of high‐efficiency alternating‐current plasma display panels (AC‐PDPs), we developed a new hoof‐type electrode structure, and we studied the spatiotemporal behavior of the density of the excited Xenon atom in the 1s5 metastable state via laser absorption spectroscopy. Using this structure, the maximum density of the excited Xenon atom per cell was improved by 2.4 times that when the conventional electrode structure was used.

Accumulation and Decay Characteristics of Exoelectron Sources at MgO Protective Layer Surface in Alternating-Current Plasma Display Panels

The accumulation and decay characteristics of exoelectron sources at a MgO protective layer surface in alternating-current plasma display panels (AC-PDPs) were investigated. The positively charged MgO surface provides a larger number of exoelectrons than the negatively charged surface, indicating that electrons trapped in shallow carrier traps coexist with trapped holes, and exoelectrons are emitted through Auger and/or photoionization processes after their recombination. The exoelectron sources are accumulated by sustain discharges and always decay. The half-life of the decay of the exoelectron sources is relatively long, of the order of a few tens of ms, confirming that the exoelectron emission property at the address discharge in a certain television (TV) field is strongly affected by sustain firings in the previous two TV fields or more. The effects of such a long-term decay of the exoelectron sources should be taken into consideration when designing the driving waveforms of AC-PDPs.

Effects of Wall Charge on Firing Voltage and Statistical Delay Time in Alternating-Current Plasma Display Panels

The effects of wall charge on firing voltage, Vf, and the statistical delay time of discharge, ts, in plasma display panels were investigated. Vf, i.e., the ion-induced secondary electron emission, is independent of both the polarity and amount of wall charge. In contrast, ts, i.e., the exoelectron emission, strongly depends on the wall charge and is smaller for a high positive wall charge, revealing the coexistence of trapped electrons and holes in the surface region. Positive charging of the MgO surface of the cathode side is effective to improve the response of the address discharge.

Analysis of transient electron energy in a micro dielectric barrier discharge for a high performance plasma display panel

We present here analysis of electron energy of a micro dielectric barrier discharge (micro-DBD) for alternating-current plasma display panel (ac-PDP) with Ne/Xe gas mixture by using the optical emission spectroscopy (OES). The OES method is quite useful to evaluate a variety of electron energy in a high pressure DBD ignited in a PDP small cell. Experiment shows that the ratio of Ne emission intensity (INe) relative to Xe emission intensity (IXe) drastically decreases with time. This temporal profile is well consistent with dynamic behavior of electron temperature in a micro-DBD, calculated in one-dimensional fluid model. INe/IXe also decreases with an increase in Xe gas pressure and a decrease in applied voltage especially in the initial stage of discharge, and these reflect the basic features of electron temperature in a micro-DBD. The influences of plasma parameters such as electron temperature on luminous efficacy are also theoretically analyzed using one-dimensional fluid model. The low electron temperature, which is attained at high Xe gas pressure, realizes the efficient Xe excitation for vacuum ultraviolet radiation. The high Xe-pressure condition also induces the rapid growth of discharge and consequent high plasma density, resulting in high electron heating efficiency.

Study on Pulse Waveforms for Improving Voltage Margin and Luminous Efficacy in an AC Plasma Display Panel Having Auxiliary Electrodes

New pulse waveforms applied to an alternating-current plasma display panel (ac PDP) with an auxiliary electrode are investigated for the purpose of improving the panel's operating voltage margin and luminous efficacy. In the proposed pulse waveforms with reciprocal sustain pulses, a pair of positive and negative sustain pulses is applied to the sustain electrodes simultaneously and alternately. A positive auxiliary pulse is applied to the auxiliary electrode immediately after reciprocal sustain pulses. The voltage margin becomes wider, and the luminous efficacy is improved because of the suppression of the discharge toward the address electrode. In the another proposed pulse waveforms with reciprocal sustain and auxiliary pulses, a negative pulse, which is the same as the negative pulse of reciprocal sustain pulses, is additionally applied to the auxiliary electrode when reciprocal sustain pulses are applied. This negative auxiliary pulse can maintain a high level of luminous efficacy because it supports the effect of the auxiliary pulses. The measurement results show that the operating voltage margin is about twice wider than that of the typical pulse waveforms for an ac PDP with an auxiliary electrode; furthermore, the maximum luminous efficacy is able to reach 3.14 lm/W in terms of the measurement of the discharge in a 50-in XGA resolution (0.27 mm × 0.81 mm) panel with a white cell and a gas mixture of Ne+20%Xe.

Correlation between the Secondary Electron Emission Coefficient of MgO Protective Layer and Luminous Efficiency in Alternating Current Plasma Display Panel (AC-PDP)

We have investigated the correlation between the secondary electron emission coefficient (γ) of MgO protective layer and discharge luminous efficiency in alternating current plasma display panel (AC-PDP) by varying the O2 flowing rates of 0, 10, 20, and 30 sccm. It is found that the secondary electron emission coefficient and the brightness are maximum, and the discharge voltage is minimum at the O2 flowing rate of 20 sccm. As a result, the discharge luminous efficiency is the highest at the O2 flowing rate of 20 sccm in comparison with others.

The Effects of Electrode Structures on the Luminous Efficacy of Micro Dielectric Barrier Discharges

A high-efficacy alternating-current plasma display panel utilizing various electrode structures is simulated using a 3-D fluid code for the investigation of the effects of cell structures on the discharge characteristics of micro dielectric barrier discharges. For the modification of the conventional coplanar electrode structure, three suggested electrode structures were simulated, namely, a patterned bus electrode, a multilayer bus electrode, and a two-electrode facial discharge structure. The time evolutions of infrared radiation images for the three structures compare well with the experimental results of test panels. The ultraviolet and visible-light emission profiles, as well as the time evolution of wall charge profiles, are analyzed in order to explain the role of the electrode structure for the improvement of luminous efficacy.