Bhum Jae Shin

Mechanism of high luminous efficient discharges with high pressure and high Xe-content in AC PDP

The mechanism of high luminous efficiency discharges with high Xe content in an AC plasma display panel was analyzed by computer simulation using a two-dimensional fluid model. The model has reproduced well the experimental results. The high luminous efficiency with high Xe content is attributed to high electron heating efficiency as well as high excitation efficiency by electron. The electron heating efficiency is increased with increasing the sustaining voltage under high Xe content and this phenomenon was analyzed by investigating the cathode sheath and secondary electron emission characteristics.

Study of various coplanar gaps discharges in ac plasma display panel

To achieve a high luminous efficacy in a plasma display panel, the display characteristics, including the luminance, discharge current, and luminous efficacy, were investigated with various coplanar gaps. The temporal behavior of the infrared emission from 80-, 150-, 200-, and 300-/spl mu/m coplanar gap discharges was also studied. The luminance and luminous efficacy increased as the coplanar gap increased until 200 /spl mu/m. However, when the coplanar gap was 300 /spl mu/m with a fixed barrier rib height of 150 /spl mu/m, the luminous and luminous efficacy suddenly decreased. This phenomenon can be explained by the results of the infrared emission observation, as the discharge shape of the 300-/spl mu/m coplanar gap became narrow when the height of barrier rib was fixed at 150 /spl mu/m. The luminous efficacy of the 200-/spl mu/m coplanar gap discharge was about 3.2 lm/W (green cells) when an Ne+4%Xe gas mixture was used as the discharge gas in the alternating current plasma display panel.

Driving waveform for reducing temporal dark image sticking in AC plasma display panel based on perceived luminance

Minimizing the reset discharge produced under an MgO-cathode condition and eliminating the wall charges accumulated on the address electrode prior to the reset period are the key factors involved in reducing temporal dark image sticking. Thus, based on the perceived luminance, new driving waveforms that can prohibit an MgO-cathode induced reset discharge or erase the wall charges accumulated on the address electrode prior to the reset period are examined for the complete elimination of temporal dark image sticking without deteriorating the address discharge characteristics. As a result of monitoring the difference in the infrared emission and perceived luminance between the cells with and without image sticking, the proposed driving waveform was shown to effectively remove temporal dark image sticking without deteriorating the address discharge characteristics

Experimental observation of image sticking phenomenon in AC plasma display panel

The itinerant strong sustain discharge that occurs during a sustain period over a few minutes causes image sticking, which means a ghost image remains in the subsequent image when the previous image was continuously displayed over a few minutes. Accordingly, this paper investigates whether the dominant factor in image sticking is the MgO surface or phosphor layer by testing the effects of image sticking in subsequent dark and bright images using a 42-in plasma display panel. When the subsequent image was dark, the image sticking was found to produce a brighter ghost image than the background. Thus, since the luminance of a dark image is produced by the weak discharge that occurs during the reset-period, the higher luminance of the ghost image was mainly due to the activation of the MgO surface. Conversely, when the subsequent image was bright, the image sticking was found to produce a darker ghost image than the background. Thus, since the luminance of a bright image is predominantly produced by the strong discharge that occurs during the sustain period, the lower luminance of the ghost image was mainly due to the deterioration of the phosphor layer.

Experimental observation of temperature- dependent characteristics for temporal dark boundary image sticking in 42-in AC-PDP

The temperature-dependent characteristics of temporal image sticking, especially temporal dark boundary image sticking, are investigated by observing the infrared (IR) emission characteristics relative to the panel-temperature rise during the reset period in a 42-in plasma television. A panel-temperature rise is induced in adjacent cells by the discharge cells (i.e., image-sticking cells) due to the itinerant strong sustain discharge, thereby lowering the firing voltage for both the adjacent and discharge cells during the ramp-up period. However, the phosphor layers in the discharge cells are deteriorated due to the strong discharge, whereas the phosphor layers in the adjacent cells are not degraded due to the absence of the strong sustain discharge. Consequently, when the displayed image is white, the temporal boundary image-sticking cells exhibit a higher luminance with a dark background image. Meanwhile, when a single color image is displayed, the temporal boundary image-sticking cells induce a color difference with a dark background image.

Effects of pre-reset conditions on reset discharge from ramp reset waveforms in AC plasma display panel

The basic characteristics of reset discharges related to a wall voltage and a priming effect were investigated under a conventional ramp driving scheme. The reset discharges could be minimized by controlling the wall voltage which is determined by pre-reset conditions. Accordingly, the current study presents a simple pre-reset condition for minimizing the reset discharge. Essentially, it is not only to reduce the duration of reset discharges but also to reduce the intensity of light emissions when the wall voltage polarity is opposite to the external voltage polarity.

Influence of Ion Bombardment on Electron Emission of MgO Surface in AC Plasma Display Panel

The influence of ion bombardment during a sustain discharge on the electron emission of the MgO surface and related driving characteristics of an ac plasma display panel were examined using the cathodoluminescence technique and SIMS analysis. The experimental results showed that severe ion bombardment predominantly sputtered Mg species from the MgO surface, thereby lowering the intensity of the F+ center peak to 3.2 eV due to the elimination of the oxygen vacancy and finally increasing the formative address delay time (Tf) due to an aggravated electron emission capability. Meanwhile, severe ion bombardment also destroyed the shallow trap level, thereby lowering the intensity of the shallow peak to 1.85 eV and eventually increasing the statistical address delay time (Ts) due to a poor electron emission capability from the shallow level. Finally, the aggravated electron emission capability from the shallow level resulted in a reduced wall voltage variation during the address period.

Case studies on temperature-dependent Characteristics in AC PDPs

The temperature-dependent characteristics of ac plasma display panels (PDPs) are investigated, based on various case studies using a conventional driving scheme with reset pulses. Though the main factor of the thermal effects is caused by strong sustain discharges, it is not only caused by the panel characteristics, but also by the temperature-dependent characteristics of the driving system. One important thermal effect is a decreased breakdown voltage due to an increase in the panel temperature. Therefore, these results may be helpful in solving image-sticking and temperature-related phenomena.

The effect of the discharge aging process on the surface state of MgO film in AC PDPs

This paper reports on the change in the surface condition of the MgO thin film in an ac plasma display panel during the discharge aging process. The superficial layer on the MgO thin film was created during the discharge aging process, which was related to the minimum sustain voltage and the light intensity emitted from the Neon+Xenon gas mixture discharge. The superficial layer on the MgO thin film was observed using a transmission electron microscope. The X-ray diffractometer pattern of the MgO thin film after the discharge aging process was different from the pattern at the beginning of the discharge aging process.

Synthesis and Characterization of Nanofibrous Polyaniline Thin Film Prepared by Novel Atmospheric Pressure Plasma Polymerization Technique

This work presents a study on the preparation of plasma-polymerized aniline (pPANI) nanofibers and nanoparticles by an intense plasma cloud type atmospheric pressure plasma jets (iPC-APPJ) device with a single bundle of three glass tubes. The nano size polymer was obtained at a sinusoidal wave with a peak value of 8 kV and a frequency of 26 kHz under ambient air. Discharge currents, photo-sensor amplifier, and optical emission spectrometer (OES) techniques were used to analyze the plasma produced from the iPC-APPJ device. Field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), gas chromatography-mass spectrometry (GC-MS), and gel permeation chromatography (GPC) techniques were used to analyze the pPANI. FE-SEM and TEM results show that pPANI has nanofibers, nanoparticles morphology, and polycrystalline characteristics. The FT-IR and GC-MS analysis show the characteristic polyaniline peaks with evidence that some quinone and benzene rings are broken by the discharge energy. GPC results show that pPANI has high molecular weight (Mw), about 533 kDa with 1.9 polydispersity index (PDI). This study contributes to a better understanding on the novel growth process and synthesis of uniform polyaniline nanofibers and nanoparticles with high molecular weights using the simple atmospheric pressure plasma polymerization technique.