Alternating-current Plasma Display Panel Research Articles

Effects of Acetic Acid on the Crystallization Temperature of Sol–Gel‐Derived MgO Nano‐Powders and Thin Films

The influences of acetic acid addition to Mg‐methoxide on the stability of the precursor and the crystallization behavior of sol–gel‐derived MgO nano‐powders and thin films were investigated using X‐ray powder diffraction, transmission electron microscopy, Fourier‐transformed infrared spectroscopy, and thermogravimetry. The addition of acetic acid enhanced the stability of the alkoxide against precipitation. Moreover, during postheat treatment of the gel powders treated with acetic acid, a significantly lowered crystallization temperature (250°C) was observed as compared to the untreated counterpart (350°C). The low‐temperature crystallization of MgO, induced by the modification of Mg‐methoxide with acetic acid, was related to the decomposition of organics at a lower temperature. These results could be explained in terms of the decrease of the O–R bond strength depending on the increase in the alkyl group size. MgO thin films having a high degree of crystallinity were successfully obtained from the Mg‐methoxide treated with acetic acid at 300°C. The low‐temperature crystallization of sol–gel‐derived MgO thin films showed the feasibility for their application as a protective layer in alternative current plasma display panel cells.

912 MgO-NiO複合材料薄膜の二次電子放出率の測定(GS-4,16 薄膜(1),研究発表講演)

In an alternative current plasma display panel (ac-PDP), the transparent magnesium oxide (MgO) protective layer plays very important roles. Improvement of the secondary electron emission coefficient of the protective layer is essential for decreasing the consumption energy of PDP. In this study, nickel oxide (NiO) was added to the MgO thin film material. The change of the secondary electron emission coefficient of the thin films prepared using the compound MgO materials was investigated. The compositions and crystalline structure of the thin films were obtained using Rutherford backscattering spectroscopy (RBS) and X-ray diffraction (XRD) method, respectively. X-ray photoelectron spectroscopy (XPS) was adopted to investigate their surface conditions. The correlation between the secondary electron emission coefficient and other properties, such as composition, crystalline structure, and surface chemical condition, was investigated. The experimental results show that the change of the concentration of the added-NiO causes the change in the surface chemical condition and the crystalline structure. Moreover, the secondary electron emission coefficient was clearly changed with the concentration of added-NiO.

The improvement of discharge characteristics and lifetime of alternate current plasma display panel by MgO deposition on the phosphor

An alternate application of MgO film for the improvement of discharge characteristics and lifetime in an ac plasma display panel (PDP) is suggested. In the normal ramp reset, the accumulated wall charges on the phosphor surface just after the reset period are different as to their color (red, green, blue) of each phosphor, which reduces the common voltage margin of ac PDP. In general, MgO is used for the protective layer of dielectrics from ion sputtering and the improvement of secondary electron emission which affects the driving voltage in an ac PDP. In this research, we deposited MgO on the phosphor to get the same addressing characteristics irrespective to the color of each phosphor, high speed addressing, and prolonged lifetime of phosphor despite the vacuum ultraviolet irradiation and ion bombardment. An optimized MgO thickness was used to avoid the excessive luminance and luminous efficacy degradation by the MgO deposition on the phosphor. Results showed that PDP with MgO coated phosphor has more uniform formative delays in address discharges and improved degradation characteristics.

Characteristics of plasma display panel with ridged dielectric and hollow gap between sustain electrodes

This article presents a front panel structure for an alternating current plasma display panel (AC-PDP) based on a ridged transparent dielectric layer and long hollow gap between the sustain electrodes. The suggested structure can reduce a firing voltage and sustain voltage than a conventional AC-PDP due to a strong electric field between the sustain electrodes. Experiments were conducted with various Xe contents from 10% to 50% at a gas pressure of 450 Torr, and the results confirmed that the ridged dielectric structure reduce the firing and sustain voltages by about 74 and 79 V at 10% Xe content than a conventional structure with 10% Xe content, respectively. Also, the proposed structure improve the luminous efficiency and luminance by about 50.9% and 33%, respectively, with a 50% Xe content when compared to a conventional structure with a 10% Xe content at a similar driving voltage.

P‐70: New Long Gap Discharge Mode Driven by Low Sustain Voltage for Highly Efficient Plasma Displays

AbstractThis paper proposes a new long gap discharge mode with a long gap of 400 μm driven by a low sustain voltage (< 200 V) for a highly efficient three‐electrode alternate current plasma display panel (ac‐PDP). Two different types of long‐gap discharge modes can be created depending on the voltage distribution among the three electrodes: a forward long gap discharge mode (FLGDM) with a high sustain voltage where the discharge is initiated from the voltage‐supplied electrode, and a reverse long gap discharge mode (RLGDM) with a low sustain voltage where the discharge is initiated from the ground electrode. As such, in the current study, a highly efficient discharge mode in a long gap was efficiently constructed under a low sustain voltage by properly controlling the amplitude and width of the auxiliary short pulse applied to the address electrode, resulting in a reverse long gap discharge mode with a high efficiency of 2.5 lm/W at a sustain voltage of 170 V.

Effects of pulsed potential on address electrode in a surface-discharge alternating-current plasma display panel

The influence of pulsed potential application onto the address electrode of an ac-type plasma display panel was investigated from the observation of front and side views of Xe atom densities in the metastable (1s5) and excited (2p) states in a unit discharge cell by using microscopic laser absorption spectroscopy and optical emission spectroscopy. It was seen that a predischarge occurs between the address electrode and one of the sustain electrode worked as a preceding anode, which is a similar effect found previously by applying a higher sustain voltage. The predischarge partially erases the surface charge accumulated in the preceding pulse, but it induces a faster main sustain discharge, bowing towards the address electrode, and enhances the production efficiency of Xe(1s5) atoms, if the applied potential is within an optimal range.

New color-enhancing discharge mode using self-erasing discharge in ac plasma display panel

A new color-enhancing discharge mode using a self-erasing discharge is proposed based on an analysis of the Ne emission mechanism in a Ne-Xe gas mixture. The effects of the new color-enhancing discharge mode produced by a ramped-square sustain waveform on improving the color reproducibility are examined in an alternate current plasma display panel (ac-PDP) filled with a Ne-Xe gas mixture. When the ramped-square sustain pulses are applied at 150 kHz, the color purities of the blue and green visible emissions are both improved, thereby expanding the color gamut area by about 5.4% without reducing the luminance.

Plasma display panels: physics, recent developments and key issues

In this paper, we describe the principles of operation of a plasma display panel (PDP) and the physical mechanisms controlling the performances of a PDP in terms of light emission efficiency, lifetime and image quality. Emphasis is put on the physics of the plasma occurring in a PDP cell, on the discharge optimization, and on the analysis of recent results provided by experimental and numerical diagnostic tools. We focus on alternative current PDPs, where the plasma is generated by a dielectric barrier discharge, the configuration adopted by most PDP companies. The recent improvements and the remaining research issues are discussed.

Improvement of color temperature using independent control of red, green, blue luminance in AC plasma display panel

This paper presents a new driving scheme for the improvement and flexibility of a color temperature without sacrificing a peak white luminance using an independent control of the red (R), green (G), and blue (B) luminance in an alternating current plasma display panel (AC-PDP). The independent control for the R, G, and B emissions can be achieved by selective application of the various narrow auxiliary pulses to the R, G, and B address electrodes during a sustain-period. The auxiliary pulses can control the luminance levels independently from the R, G, and B cells by forming the fast and efficient plasma or by slight disturbing of the wall charge accumulation. By the application of various auxiliary pulses leading to the simultaneous control of each color's luminance, it is observed that the new driving scheme can improve the color temperature from 5396 K to 10 980 K in a 4-in test panel with almost the same peak white luminance as that of the conventional driving scheme.

交流(AC)型プラズマディスプレイの放電特性と技術開発

Comparison of luminosity-modulation switching principles in matrix displays showed that an AC-PDP (alternating-current plasma display panel) can produce 30 to 50-inch diagonal displays of superior motionpicture quality and of a low price. Comparison with a process plasma and a thermonuclear fusion plasma showed that an AC-PDP plasma in each cell has extremely low degrees of ionization, uniformity, and steadiness. The mechanism of VUV (vacuum ultraviolet) production in an AC-PDP was theoretically studied, and ways to increase VUV production efficiency were discussed. It was then shown that the development of a vertical discharge AC-PDP of low driving voltage is expected and that precise and dynamic control and measurement of the non-uniform and non-steady discharge-radiation process will become even more important in the future development of new AC-PDP technologies.

Plasma Propagation Speed and Electron Temperature in Surface-Discharged Alternating-Current Plasma Display Panels

Space and time resolved discharge images from an alternating-current plasma display panel have been observed by a high-speed single-frame camera to investigate the electron temperatures. The plasma propagation speed on the cathode was measured to be 0.9 mm/µs and 1.3 mm/µs, respectively, and that on the anode was measured to be 1.8 mm/µs and 2.7 mm/µs, respectively, at driving frequencies of 50 kHz and 100 kHz. This finding indicates that the electron mobility on the anode is approximately two times the ion mobility on the cathode. Particularly, the electron temperatures in alternating-current plasma display panels (AC-PDP) were found to be 1.2 eV and 2.5 eV at driving frequencies of 50 kHz and 100 kHz, respectively, in this experiment, which are in good agreement with those obtained by a micro-Langmuir probe and the laser Thomson scattering method.

3‐D simulation of T‐shaped electrode and comparison of results with experiments

Numerical simulation is one of the most useful tools to study gas discharge phenomena that occur in alternating current plasma display panel (AC‐PDP) cell. Most PDP cell simulations have been performed for two‐dimensional cell, is cross‐section along the address electrode. We developed a three‐dimensional PDP simulator and applied it to a T‐shaped electrode cell in order to show the effects of sustain electrode shape that cannot be included in two‐dimensional simulation. The dependence of power consumption on electrode shape and area in the simulation showed the same trend as experiment.

Influence of Vacuum-Annealing Process on the Secondary Electron Emission Coefficient (γ) from a MgO Protective Layer

The secondary electron emission coefficient (γ) of vacuum-annealed MgO films has been investigated using a γ-focused ion beam (γ-FIB) system. The vacuum-annealed MgO films have been found to have higher γ values from 0.05 to 0.12 than those from 0.03 to 0.06 for as-deposited MgO films for operating Ne+ ions whose acceleration voltages ranged from 50 V to 200 V. It is shown that the γ for the as-deposited MgO protective layer is significantly decreased by the influence of holding in air since the hydroxyl OH groups are absorbed onto the MgO surface from the atmospheric air. It is also observed that the secondary electron emission coefficient γ for the vacuum-annealed MgO protective layer is less influenced by holding in air than that for the as-deposited MgO protective layer. Based on these findings, it is concluded that the vacuum-annealed MgO protective layer plays an important role in lowering the firing voltage in alternating current-plasma display panel (AC-PDP) compared with the as-deposited MgO protective layer or the as-deposited MgO protective layer held in air.

Improvement of luminance and luminous efficiency using address voltage pulse during sustain-period of AC-PDP

To improve the luminance and luminous efficiency of a surface-discharge alternate current plasma display panel (ac PDP), auxiliary voltage pulses were applied to the address electrode during a sustain-period. The luminance and luminous efficiency exhibited maximum values at an address voltage of 100 V and pulse width of 1 /spl mu/s. An improved luminance of 21.4% and luminous efficiency of 24% were simultaneously obtained based on the proper adjustment of the widths and amplitudes of the address voltage pulse. Accordingly, the proper control of the amplitudes and pulse widths of the auxiliary address voltage during a sustain-period can improve both the luminance and the luminous efficiency in a surface-discharge ac PDP.

P‐41: The Measurement of the Electric Field in a Surface‐Type AC Plasma Display Panel Cell by Laser‐Induced Fluorescence Spectroscopy

AbstractThe temporal variations of the electric field in a surface‐type AC (alternating current) PDP (plasma display panel) cell were measured using the laser‐induced fluorescence spectroscopy. The wall voltage showed dynamically different behavior dependent upon the discharge condition during the pulse‐on and the pulse‐ off period. The wall voltage decreased as the MgO surface of the panel was deteriorated by the discharge and this phenomenon caused the increase of the minimum sustain voltage.

Effects of plasma emission on optical properties of phosphor layers in surface-type alternate current plasma display panel

This study uses helium and xenon gas mixture discharges to determine the effects of helium plasma emission on the characteristics of the visible emission from the stimulation of the red, green, and blue (RGB) phosphor layers in a surface-type alternate current plasma display panel. With a mixture of less than 2% xenon to helium, it was found that the luminance of the RGB phosphor layers decreases with a decrease in the helium plasma emission intensity. However, with a mixture of above 2% xenon to helium, the luminance of the RGB phosphor layers increases regardless of a decrease in the helium plasma emission intensity. Furthermore, the color purity of the RGB phosphor layers improves as the helium plasma emission intensity decreases. Accordingly, it can be concluded that the optical properties of the phosphor layers, including color purity and luminance, depend on the helium plasma discharge emission as well as the visible emission from the stimulation of the phosphor layers.

Surface discharge characteristics of MgO thin films prepared by RF reactive magnetron sputtering

Abstract This paper describes the surface glow-discharge effect of MgO thin films prepared by reactive radio-frequency planar magnetron sputtering on the dielectric layer of an alternating-current plasma display panel. By introducing an MgO coating on the dielectric the discharge voltage decreases sharply, although the thickness is only a few tens of Angstroms. The lowest discharge voltage is obtained for the sample prepared at a 30% O2 content in an O2+Ar gas mixture and at a sputtering gas pressure of about 5 mTorr. Moreover, high transparency (∼95%) is also obtained under the same experimental conditions. The samples prepared show more sputter-resistant properties than samples prepared by the electron-beam method and no cracks are observed on the surface after post-deposition annealing.

MgO powders for protective layer of alternating current plasma display panel

AbstractThe MgO powder used for a screen‐printed protective layer on plasma display panels was evaluated. The MgO powder was formed by either vapor‐phase oxidation or decomposition of Mg(OH)2. For the same BET value, the diameter of MgO particles formed by the latter method was larger than that by the former method. It was found that the particle diameter calculated by Scherrer's equation using the half‐value width of an X‐ray diffraction pattern was less than one‐fifth of that calculated using the BET value. When the distribution of the particle size was evaluated by the centrifuge precipitation method, it was found that both the median and modal diameters of the MgO powders formed by the latter method were larger than that by the former method. The powder formed by the latter method also contained powder with diameters of less than 20 nm; the weight ratio of the fine powder to the entire MgO powder was 5.5 ∼15.9 wt%. The transmission electron microscopy (TEM) observation revealed that the powder formed by the former method had a higher crystallinity and that the powder formed by the latter method tended to aggregate. When protective MgO layers were fabricated by sintering MgO powder formed by the above two methods, the powders oriented in the (111) orientation and the MgO formed by the former method had a higher crystallinity. It was concluded that, since the MgO powder formed by the former method (vapor phase method) had a finer particle diameter, higher crystallinity, and higher uniformity than the powder formed by the latter method (decomposition of Mg(OH)2), the MgO powder formed by the former method is more suitable for the alternating current plasma display panel (AC‐PDP) printed protective layer.