Norihiro Uemura

Theoretical formulation of the vacuum ultraviolet production efficiency in a plasma display panel

The theoretical formulation given in this article allows the vacuum ultraviolet (VUV) production efficiency to be calculated from the electron temperature of the plasma and the gas parameters including gas mixing ratio, excitation energies, and excitation cross sections using the separately determined conversion efficiency of the plasma input power into the electron heating power. The VUV production efficiencies calculated for (Ne+Xe) mixture (neon (Ne) and xenon (Xe) mixture) discharge gases using the formulation show that the efficiency can be increased by decreasing the electron temperature and by increasing the amount of Xe in the gas mixture. A method for determining the electron temperature of the plasma display panel (PDP) plasma from emission intensity measurements was also given, and was used to show that the electron temperature in the ordinary PDP plasma is 3 eV.

Electronic energy states in Si-doped MgO for exoelectron emission

A generalized analytical method to determine the density of energy states of electron emission source (EES) is devised by using a thermal excitation and emission model for an exoelectron in the MgO layer and the emission time constants of the exoelectron extracted from experimental stochastic distributions of discharge delay time. When applied to Si-doped MgO, the emission time constant of the exoelectron from the Si EES becomes shorter at high temperature and at short time intervals due to thermal excitation. The density of energy states of the Si EES DSi(E) shows the main peak at 736 meV, a satellite peak at 601 meV, and broad energy structures over the range of 586–896 meV. The effective number of Si EES is 5.5 times larger than that in purified MgO. The excitation energy in a Si-doped MgO cluster with a crystal structure is obtained to be 0.83 eV by using the symmetry-adapted-cluster configuration interaction method and the Si EES contributes to exoelectron emission. The thermal excitation is governed...

Numerical analysis of density of energy states for electron‐emission sources in MgO

— An analytical method to determine the density of energy states of electron-emission sources (EESs) in chemical-doped MgO is described using a discharge probability model and a thermal excitation and emission model. The density of energy states for multiple types of EESs is represented by using a linear combination of Gaussian functions of which parameters are determined by the theoretical emission time constant of an exoelectron and statistical delay time ts extracted from experimental stochastic distributions of discharge delay time in plasma-display panels. When applied to Si-doped MgO, the effective number of Si EES is calculated to be 1.8 × 106 per cell. The average and standard deviations of activation energy have an energy level of 770 meV and a large value of 55 meV. In Si and H co-doped MgO, the high peak density of [H2−]0 appears at 550 meV. ts at the short time interval of 1 msec decreases and is independent of temperature due to exoelectron emission from the [H2−]0. The dependence of ts at a time interval of 10 msec on temperature becomes weak because the energy structure of the Si EES broadens significantly attributed to the electrostatic effects of the doped H atoms.

Emission Time Constant of Exoelectron and Formative Delay Time Analyzed by Using Discharge Probability Distribution

A discharge probability model is proposed to analyze the stochastic distribution of the discharge delay time. The distribution is described as a hybrid function between the exponential and Gaussian distributions and their characteristic properties, such as the emission time constant of an exoelectron and the average and standard deviations of the formative delay time. The calculated results of the probability of a successful discharge show a good agreement with the experimental results measured in plasma display panels. The analytical protocol allows the discharge delay time to be accurately separated into the statistical and formative delay times. A thermal excitation and emission model is devised to analyze the effective number and the activation energy of electron emission sources (EESs) in a MgO layer using the emission time constant of an exoelectron. The effective number of the EES, i.e., 3.79 × 105 per cell, decreases after a long time interval because of the thermal excitation; thus, the emission time constant increases significantly. The effective number of the EES after 1000 h of sustain discharge decreases to 2.07 × 104 per cell, which is 0.055 times that before the sustain discharge. This degradation is explained by 2.6-4.3 times of increase in the density of electron traps due to the ion sputtering of noble gases against the MgO surface. The emission time constant is found to decrease to 0.45 times when the wall voltage near the MgO surface is increased by 11 V, which demonstrates that the exoelectron emission can be controlled by the electric field.

Ultraviolet Production Efficiency of AC‐PDPs and Ways to Increase It

The mechanism of VUV production in an AC‐PDP was theoretically studied, and ways to increase VUV production efficiency were discussed. It was then shown that precise and dynamic control of the non‐uniform and non‐steady discharge‐radiation process will become even more important in the future development of new AC‐PDP technologies.

7.4: Reduction of Address‐Delay‐Time Degradation by Half‐Pitch Shifted Priming Cell Structure in AC‐PDPs

A half-pitch shifted priming cell structure to reduce address-delay-time degradation and lower power consumption has been developed. Discharge transition from a priming cell to a display cell occurred. The time constant of priming electron emission only from the priming cell did not degrade. Observed address-delay-time degradation in the display cell reduced.