Versatile energy recovery circuit for driving AC plasma display panel with single sustain circuit board

This paper presents an energy recovery (ER) circuit which can operate either in a series or a parallel resonance mode and can drive an AC plasma display panel (PDP) with a single sustain circuit board. The proposed ER circuit consists of one energy storage capacitor, two energy recovery inductors, and three insulated-gate bipolar transistors. The circuit operations in the series and parallel resonance modes are similar to conventional ones, except for the leading edge of the first sustain pulse and the trailing edge of the last sustain pulse. To reduce power consumption in the parallel resonance mode of operation, these two pulse edges are generated using a series resonance between the panel capacitance and the energy recovery inductor. The proposed circuit had energy recovery efficiencies in both the series and parallel resonance modes that were nearly the same as the efficiency of the conventional series resonance ER circuit. Experimental results on a 42-inch XGA single-scan PDP show that the proposed ER circuit is suitable for use in a PDP drive circuit.     

Power-efficient drive circuit for plasma display panel

This paper proposes a power-efficient drive circuit for plasma display panels (PDPs). The proposed circuit reduces reactive power consumption by varying the inductance for energy recovery and by separating the grounds of the sustain and data drivers. Power consumption due to discharge current is reduced by using two soft-switching inductors for the pull-up switches in the bridge circuit. Power consumption for data addressing is reduced by using a dc voltage source to bias the ground for the sustain driver. The proposed circuit was tested on a 50″ full-HD single-scan PDP which had a sustain discharge gap of 80 μm; total power consumption to display the dynamic broadcasting content of IEC 62087 was ∼40 W (14.5%) less than that required by the conventional drive circuit, and the EMI level for 2 < f < 9 MHz was reduced significantly. The experimental results demonstrate that a high performance power-efficient PDP drive circuit can be built using the proposed method.     

Cell parameter extraction method for AC plasma display panels

This paper presents a cell parameter extraction method for three-electrode AC plasma display panels (PDPs). This method uses three different two-electrode AC discharges to extract the cell capacitances. The drive point capacitances of the cell with and without a two-electrode dark discharge were measured, and the cell capacitances were extracted from them. The extracted cell capacitances agree well with those obtained from a three-dimensional electromagnetic simulation. Electrical equivalent circuits of the plasma were constructed using Jung's model [Y.K. Jung, J.W. Seo, Y.H. Kim, B.K. Kang, Circuit model for two-electrode AC discharge, IEEE Trans. Plasma Sci., 31(3), pp. 362–368, 2003.] and the measured firing voltages. A circuit model for the cell was constructed using the cell capacitances and the equivalent circuits for the plasma. The results of electrical simulation using this circuit model agree well with the measurements, indicating that the presented circuit model would be useful for simulating the electrical behaviors of a three-electrode AC PDP.     

Glass barrier ribs for a transparent AC plasma display

Abstract— Transparent glass barrier ribs are proposed for the development of a transparent plasma display. Glass barrier ribs were fabricated via a wet‐etching process with a 20% hydrofluoric acid. Two different etching methods for glass barrier ribs are investigated: a single‐sided etching method and a double‐sided etching method. Simulation and measurement results show that glass barrier ribs formed by the double‐sided etching method are more transparent compared to those formed by a single‐sided etching method. A fabricated transparent AC plasma display with glass barrier ribs showed good transparency and was operated by using a conventional driving scheme.     

Biased scan of plasma display panel for data voltage reduction

This paper proposes a method of reducing the data voltage V_d of plasma display panels (PDPs). The proposed biased-scan method uses two separate ground systems: one for the sustain pulse generator (FGND) and the other for the data address and control systems (CHGND). A dc voltage bias, which is applied between CHGND and FGND during the address period, reduces V_d while preventing the undesired glow discharge induced by a scan pulse only. CHGND is connected to FGND for the first sustain pulse of each subfield, which reduces the time lag of address discharge, but it is separated from FGND for the other sustain pulses to increase the margin of the sustain voltage. The proposed method was tested on a 15% Xe 50-in. Full HD (1920 × 1080) single-scan PDP which had a sustain discharge gap of 110 μm. V_d could be reduced by 20 V (30%), and the power consumption of the V_d voltage source decreased by ∼25 W (50%) from that of the conventional method.     

Flat panel detector based on a shadow mask plasma display panel

A flat panel detector based on the structure of a shadow mask plasma display panel is analyzed in terms of the electron amplification factor when used in the Townsend mode. The detector consists of a metal shadow mask and two ultra‐thin glass substrates with electrodes depositing on them. The shadow mask divides the detecting area into arrays of independent cells. The electron gain and linearity of the device are investigated by simulation based on the particle‐in‐cell/Monte Carlo collision model. Similar experiments are carried out. Both experimental and simulation results show that the linearity of the detector is significant. The applied voltages and the effective cathode area are parameters affecting its gain. As the avalanche process in the center of the cell with small electric field strength is much smaller than that near the shadow mask edge, the gain increases exponentially with the anode voltage but decreases with the negative shadow mask voltage. The balance between effective cathode area and high electric field intensity near the shadow mask edge provides room for future optimization of the detector. In conclusion, the flat panel detector is a promising component in a detection system for high energy radiation, and the wide application of the device is expected.     

Fabrication and characterization of Pb-free transparent dielectric layer for plasma display panel

Glasses within the Bi₂O₃–B₂O₃–BaO–ZnO system were examined as potential replacements for PbO-based glass frits with low firing temperatures. These frits are used in the transparent dielectric layer of plasma display panels (PDP). The glass transition temperature (T_g) of the prepared glasses varied between 450 and 460 °C. These glasses display dynamic dielectric properties, high transparency and thermal expansion as well as matching well with substrate glass. The thermal coefficient of expansion (TCE) was with the desired range of 81–86×10⁻⁷/K. Moreover, when the screen printed film was heat-treated at 570 °C for 30 min, optical transmittance (83%), root-mean square (rms) roughness (177.6 Å), dielectric constant (10.25) and withstand voltage (4.15 kV) satisfied the requirements necessary for transparent dielectric layers to be used in PDP applications.     

Application of AC plasma display panels to radiation detectors

Radiation detector proposals that use plasma display panels are rare. In this work, we confirmed a radiation detector that uses plasma display panels that are focused on the breakdown voltage shift in the ramp waveform. We adapted the cell structures, gas contents, and waveforms of plasma display panels (AC‐PDPs) for radiation detectors. Hard X‐rays and gamma rays induce electron emission into the discharge gas, resulting in generating electrons, electron multiplication, and charge accumulation on dielectrics. The radiation dose rate of hard X‐rays and gamma rays (Cs137) is measured as a breakdown voltage shift between anodes and cathodes. For gamma rays, the detection sensitivity in this experiment is not as high as in the case of hard X‐rays, but the detector can locate gamma rays. These results suggest that adapted AC‐PDPs can detect both hard X‐rays and gamma rays and can be used in a large two‐dimensional radiation detector.     

Effect of single crystalline MgO powder treatment of phosphor surface on discharge property of high-Xe AC plasma display panels

This paper presents a method of surface treatment of phosphor using a single crystalline MgO powder, and investigates effect of the surface treatment on discharge property of a plasma display panel (PDP). The discharge gas of the PDP was a 88% Ne–12% Xe gas mixture at a pressure of 400 Torr. For the surface treatment, a single crystalline MgO powder was mixed in methanol, sprayed on the phosphor surface, and annealed at 400 °C. This treatment suppressed glow discharge, which was observed very often in the weak discharges for reset of PDP if the phosphor works as a cathode, and provided a favorable condition for the PDP reset operation. When an experimental PDP fabricated using the surface treatment was driven by the twin reset waveform, the measured time delay for 99.9% cumulative probability of address discharge was 830 ns, which meets the timing requirement for addressing a Full HD (1920 × 1080 resolution) PDP with the 10 sub-field single scan method.     

Influence of wall charge on image sticking phenomena in AC plasma display panels

This paper investigates the image sticking phenomenon in an AC plasma display panel (PDP), which appears when the PDP is subjected to a strong sustain discharge for an extended time and leaves a residual image on the display. This problem is very difficult to resolve using a conventional reset. Image sticking was investigated by observing the light emission from the reset, indicating that the wall charges accumulated on the sustain electrodes were the major cause. A few face (plate-gap) discharges equated the wall voltages on the sustain electrodes and set all cells of the PDP at the same external voltage for firing a surface discharge. The image sticking phenomenon disappeared after the face discharges.     

Carbonation reaction of (Ca,Mg)O protective layer on plasma display panel

We have been applying a low discharge voltage (Ca, Mg)O protective layer to plasma display panels to reduce their power consumption. However, (Ca, Mg)O is highly reactive with CO₂, and the resulting carbonate formation during high‐temperature panel sealing in air impairs the low discharge voltage characteristic. We investigated the mechanism of the carbonation reaction that occurs on a (Ca, Mg)O surface during annealing in air at 450°C and found that the CO₂ diffuses through the formed CaCO₃ layer and that a (Ca, Mg)O + CO₂ → CaCO₃ + MgO reaction then occurs. This carbonation reaction evidently stops when the growing MgO finally forms a layer at all boundaries between the CaCO₃ and (Ca, Mg)O regions.     

Two-stage dither to enhance gray scales based on real-time motion detection in plasma display panel

In order to reduce gray scale loss in low and middle-high gray scale ranges which are caused by inverse gamma conversion and limited gray scale method for dynamic false contour (DFC) improvement, respectively, and enhance gray scales both in static and moving regions of an image, two-stage dither based on real-time motion detection method is proposed. Firstly, the image is divided into blocks, and the motion state of each image block is detected according to real-time motion detection method. So limited gray scale method to improve DFC can only be used in moving image blocks. Then, ordered dither and random dither combined with minor pixel separation (MPS) are used to improve gray scale loss caused by inverse gamma conversion and limited gray scale method, respectively. The experimental results show that motion detection can be implemented easily and the detection accuracy is more than 99.3%. The gray scales in moving and static image regions are all expressed smoothly while DFC is markedly improved.     

Floating drive schemes for dual-frequency addressing of complex liquid crystal displays

A circuit configuration for the dual-frequency addressing of complex liquid crystal matrix displays is described. After division of the high and multilevel drive voltages into several digital signal components, they are superposed in digital 15 V CMOS ICs. The signals so produced have an amplitude which exceeds the value of the supply voltage and which involves three or four levels. The technique is suitable for modification of existing display drive systems to reach a higher number of multiplexed lines or to allow better selection.     

The enhancement of the BRCR (Bright Room Contrast Ratio) in a plasma display panel

Luminous efficiency and Bright Room Contrast Ratio (BRCR) are critical issues in a plasma display panel. In the conventional PDP panel structure, an optical filter is used to reduce the reflected luminance and to increase the BRCR. However, this optical filter reduces the peak luminance also, resulting in a decrease in the luminous efficiency. In this study, a new electrode structure with the enlarged black stripe and the auxiliary electrode between the bus and ITO electrode was proposed to investigate the possibility of getting higher BRCR without an optical filter. The experimental results using 3 in. test panels in this study showed that the BRCR of the new structure was enhanced to more than twice of that of the conventional one without any loss of the luminous efficiency.     

Effects of Xe content on wall‐voltage variation during address period in AC plasma‐display panel

Abstract— To investigate the influence of the gas condition, especially xenon (Xe) gas, on the wall‐voltage variation in relation to the electric‐field intensity during the address period, the wall voltages were measured under various Xe‐gas content ranging from 11 to 20% by using the V^t closed curve analysis method. It was observed that under a weak electric‐field intensity between the scan and address electrodes, the change in Xe content did not affect the wall‐voltage variation, even at a higher panel temperature of 65δC. However, under a strong electric‐field intensity, the wall‐voltage variations were reduced with an increase in the Xe content, confirming that a higher electric‐field intensity would be required to induce the wall‐voltage variation at a higher Xe content during the address period.     

裸眼3D LED显示的全息透镜板在线拼接的检测方法

全息透镜板的高精度拼接与装配是基于全息透镜技术的大屏幕LED裸眼3D显示系统搭建中的关键问题。理论计算与实验结果表明,全息透镜板与LED显示模组横向相对位置误差小于1.332mm时,可以满足显示的要求。基于裸眼3D显示系统的投射条纹,提出了基于投射条纹的全息透镜板位置实时调整方法。依据此方法提出了基于极大值测量条纹中心间距的图像处理算法,并结合LabView编写了图像处理程序。实验结果表明,使用该方法测得的亮暗条纹间距的测量精度为0.1mm,反算出全息透镜板与LED屏之间的位置误差小于0.03mm,满足实时调整全息透镜板位置的要求,可以作为全息透镜板在线拼接的检测方法。     

Influence of wall charge distribution on time lag of address discharge in AC plasma display panels

The influence of wall charge distribution on the time lag of address discharge in an AC plasma display panel is investigated using two different reset waveforms: one (typical reset) induces both face and surface discharges and the other (TR reset) induces face discharges only. The measured formative time lag and statistical time lag of address discharge for TR were 21–31 ns and 31–74 ns shorter than the one for the typical reset, respectively. The TR reset resulted in much less increase of statistical time lag than the typical reset when the reset-to-address time interval was increased, and 70 ns smaller deviation of the statistical time lag among different color cells. Calculations show that the TR reset forms a much smoother wall charge profile, which is less susceptible to cell parameter variations, than the typical reset. The observed differences in the time lags of address discharge between different scan lines and color cells are strongly correlated to the differences of the wall charge profile, indicating that a smooth wall charge profile formed by the reset using face discharges only reduces the time lag of address discharge and minimizes the susceptibility of address discharge to cell parameter variation.     

脑力驱动残疾人轮椅与脑电波图像显示设计

结合嵌入式系统和脑-机接口技术,构建脑力驱动残疾人轮椅系统。首先利用脑电信号(EEG信号)的采集芯片装置TGAM对脑电信号进行采集;其次通过蓝牙模块将TGAM和计算机相连接,将采集到的脑波原始数据传输到计算机上,利用e Sense算法将脑电数据进行量化;然后再通过蓝牙无线连接到Arduino轮椅控制平台,通过I/O控制口实现脑力对轮椅的控制;最后提出采用多语言混合编程的方法实现脑电信号的图像显示,相比单一语言编程的图像显示,多语言混合编程法更好地显示了脑电信号的三维图像。