Measurement of wall charge and capacitance variation for a single cell in the AC plasma display panel

Real-time dynamic measurements are performed on a single cell in a standard commercially available large plasma panel. The measurements determine cell response to variations in address pulses, sustain waveforms, or priming from neighboring cells. The wall-charge measurement indicates the internal dielectric surface charge and the capacitance measurement indicates the existence of a plasma in the gas volume. These measurements have shown that neighboring on cells can cause a large wall-charge transfer in off cells that results in reduced write and sustain voltage margins. Direct wall-charge measurements allows use of a simple technique for determination of the voltage transfer curve of the plasma cell which greatly aids device characterization. The capacitance measurement has shown that a plasma exists in commercial MgO panels for 10-15 µs after the discharge-current peak. The capacitance and wall-charge measurements can be combined to give simultaneous real-time results.     

The differential voltage pen for plasma panels—A light pen substitute

A new hand-held interactive pen for ac plasma panels is described. The pen uses multiple metal plates to detect positional information generated by the regular write/erase voltages in the panel. No optical detector is used. Closed-form field potential equations of a panel line outside the panel are derived. These equations enable the resolution of the pen to be optimized; they are also helpful in pointing out some avoidable troublesome secondary effects. It is shown that a multiple plated probe's resolution is seven times better than that of a single-plate probe. This new pen can achieve resolutions to within 1 cell on panel artworks as dense as 50 lines/cm. Worst case detect time is 100 ms for a one million cell panel. Difficulties and special panel requirement when applied to a panel display product are discussed.     

Optical write-in for the plasma display panel

Techniques of changing the state of plasma display cells with externally applied light are presented. Optical write-in offers the advantage of high-speed parallel data transfer from a photographic transparency to a plasma display panel. It is established that light incident on a plasma cell causes a photoemission from the inner glass surface. The emitted electrons perturb the wall voltage and cause a change in state. The intensity of light needed to change the state of cells can be reduced, without changing the solid panel materials, by two techniques, Electron avalanches initiated by the photoelectrons can be used to decrease the light needed by a factor of 100. By flashing light during the plasma display cell gas discharge, the intensity of the light can be further reduced.     

Dynamic keep-alive to improve plasma-panel write and sustain margins

Keep-alive border cells are used to prime addressed cells of a plasma panel to improve the write margin. Currently, the time relationship between the drive waveform for the keep-alive border and the write waveform is kept fixed or static. The effectiveness of the static keep-alive arrangement is very limited: e.g., an experiment is described showing that across a 2.4-in span (between keep-alive border and address cell), this breakdown voltage increases by 14 percent and the ionization time almost doubles. These spatial variations greatly reduce the operating margins. A dynamic keep-alive scheme has been designed to provide spatial uniformity of breakdown voltage and ionization time, and thus to improve the write margins. It can be implemented by simply using the most-significant bits of an address to control the firing of a single keep-alive driver. Experimental results show that for a 5 × 5-in panel, the dynamic keep-alive scheme provides about 50-percent improvement in write margin over the static keep-alive arrangement. Some of this write margin can be traded to provide increased sustain margins.     

A solid-state matrix-addressed display

Cadmium selenide (CdSe) switches have been devised to control the luminous emittance of electroluminescent cells in a solid-state display. The technique employed makes use of the hysteresis in CdSe to change the resistance of the material to some low value when a switching voltage is applied. In its low-resistance state, the CdSe switch can energize an electroluminescent cell connected in series with it. By wiring the cells in rows and the switches in columns, a display panel results in which each cell-switch combination can be individually addressed by energizing the appropriate row and column. This paper describes the principles of operation and outlines the construction techniques for this display. Performance characteristics of a 100-unit display panel are discussed. This panel, with 20 lines per inch resolution, has been operated with addressing pulses of 25 microseconds duration, providing an output brightness of 20 footlamberts. The construction process is adaptable to mass production, resulting ultimately in low cost. The display has memory thus allowing random access, and operates on very little power. Demonstration of this display represents a significant advancement in the state of the art. This small display possesses the characteristics necessary for development of practical large-area displays.     

Charge spreading and its effect on AC plasma panel operating margins

Like normal wall charges in an ac plasma panel, the spread charges from neighbor "on" cells to an "off" cell site can cause an increase or decrease in the required write voltage depending on the relative location of the write pulse with respect to sustain pulses. The net changes in write voltage can be accurately measured. The results obtained show that spread charges increase sharply with panel resolution and have a dominant influence over other priming effects on operating margin, e.g., to compensate for the wall voltage due to spread charges, an additional 15.5 V, or 10 percent of the voltage used to write an isolated cell, is required to write a cell which is located in the middle of a cluster of"on" cells on a high resolution 512-60 panel.     

Single flux, quantum B flip-flop and its possible applications

We are introducing a new subfamily of rapid single-flux-quantum (RSFQ) digital cells, based on a single B flip-flop template. The template can be considered as an SFQ flip-flop with up to 4 inputs and 6 outputs. Each input SFQ pulse can change the flip-flop's internal state. Each output presents (in the form of SFQ pulses a specific logic function of the initial state of the cell and input signals. Simple connection of various inputs and/or outputs, combined with shortening or opening of certain branches of the template allows one to implement a variety of RSFQ cells with wide margins. Of these various RSFQ cells, we have designed and successfully tested the T1 cell (asynchronous toggle flip-flop with synchronous destructive readout), single-bit full adder, and single-bit stage of an up-down counter. Experimentally measured margins for dc power supply voltage for these circuits were ±24%, ±24%, and ±17%, respectively     

State inversion of plasma panel cell

Two pulses applied in sequence to a cell of a plasma panel cause inversion of the state of the cell. The first, an inverting write pulse Vwi, narrower than a normal write pulse and positioned within the discharge recovery time ahead of a sustain pulse, can cause a cell to switch "on" in such a way that the cell wall voltage builds up to its steady-state value gradually over several sustain cycles. The second is a conventional erase pulse Ve. If the cell is initially "on," Vwihas no effect while Veinverts the cell to the "off" state. On the other hand, if the cell is initially "off," Vwicauses a low-level discharge such that the wall voltage is too low at the time Veis applied to the cell to cause a discharge, but the wall voltage keeps building up to a steady "on" state through a number of sustain cycles. Thus Vehas no effect and the cell remains "on." Using the state inversion, a blinking cursor has been successfully demonstrated on an 80 × 256 plasma panel. Negative image and bandwidth reduction in bilevel picture transmission could also be achieved with state inversion.     

Smectic liquid-crystal flat display with light-pen and readout functions

A thermally addressed smectic liquid-crystal flat display is described, which is addressed by a laser-diode light pen as well as by the usual heating electrodes. Information can be written manually on the display panel using a laser diode or information generated by external equipment can be displayed by resistive heating in a line-at-a-time sequence. The manually written information can also be read out electrically by detecting the capacitance of each pixel. To detect the pixel's capacitances arranged in X-Y matrix form, we describe a scheme to prevent crosstalk and to avoid the influence of the electrodes' resistance. By using these techniques, we constructed an experimental display, It has a 30 × 40 mm²display area and a resolution of 4 lines/mm.     

Multiple states and variable intensity in the plasma display panel

The plasma display panel, in its usual mode, retains information in the form of wall charges that determine whether or not a sequence of discharges will be maintained at a given cell. These discharges are stable in the sense that a perturbation in wall voltage at a particular discharge will damp out over the succeeding discharges. Recent work has shown that a cell in a plasma display panel can exist in one of several states, each with a unique set of wall voltages and each with a unique average intensity. As with the bistable case, each state is stable in the sense that perturbations damp out. Three states have been achieved simultaneously, with brightnesses that can be characterized as bright, medium, and dim. Within the constraints of a simple theoretical model, the conditions for stability can be stated in terms of the products of the slopes of charge transfer curves. This technique for achieving variable intensity retains the advantage, inherent in the plasma display technique, that the information, once imparted to the display, is retained as long as the sustaining signal is applied to the entire panel.     

Bidirection shift plasma display requiring less than 20 drivers

A bidirection shift technique has been successfully demonstrated on a 512 × 120 cell array of a standard ac plasma panel. The key features of the bidirection shift technique are: electron transport for efficient information transfer, preset wall voltage for select-shift and timed select-erasure for automatic error clearing. The technique reduces the number Of line drivers to 2 four-phase drivers and 7 line drivers. A shifting speed up to 800 characters/s has been achieved with good operating voltage margins.     

Realization of Flexible Plasma Display Panels on PET Substrates

DC plasma display panels are fabricated on flexible polyethylene terephtalate (PET) substrates. Each pixel consists of laterally placed anode and cathode electrodes. All electrical elements are formed on a single PET substrate, whereas a second substrate is needed to encapsulate the panel. Silver is used as the metal for each electrode and standard photolithography is used to form each cell. A 150-/spl mu/m-thick layer of a UV-curable polymeric adhesive was used to form barrier ribs to both electrically isolate neighboring cells and to encapsulate the plasma. Conversion of vacuum UV into visible light is possible by blast-embedding of proper phosphor grains into the top substrate. The current-voltage and turn-on voltage versus pressure characteristics are examined. Effect of curvature on turn-on voltage is addressed.     

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.     

Electron transport self-shift display using an AC plasma panel

Using an electron transport mechanism, a self-shift display has been successfully implemented on an ac plasma panel providing higher resolution, higher shifting speed, and wider operating margins than previously obtained. The mechanism consists of a unidirectional and efficient transport of a large portion of electrons (generated during the display site discharge) to a neighboring OFF transfer site by a low transverse voltage. The process results in a large wall voltage build-up at the transfer site to switch its state from OFF to ON. The implemented electron transport self-shift display consists of a 7 × 128 site array of an Owens-Illinois 60 lines per inch panel where the 128 columns are driven by a four-phase driver. A resolution of one display site for every two electrodes and a shifting speed better than 600 characters per second have been successfully demonstrated. The ranges of the shifting voltages VDand VTare better than 15 V over a 10-V sustain range. The shifting operation also was successfully demonstrated on an 83 lines per inch panel with good operating margins.     

Ternary operation of the plasma display cell

The plasma display cell, in the normal mode, operates as a bistable ON-OFF element. Under certain conditions, by applying the appropriate sustaining signal, the cell can be maintained in one of several possible ON states that can be distinguished from each other by the light or current output of each state. Conditions on a class of sustaining signals that can sustain the cell in two ON states and an OFF state are described.     

Luminance control method for a given gray level by asymmetric sustain pulses in AC PDP

A possible method to control luminance of a whole panel in an ac plasma display panel (PDP) is to control a total number of sustain pulses which is called as gray level control. However, this method leads to rough step-like luminance control especially in the low gray level. In this paper, a simple and robust luminance control method of whole panel is proposed. The key feature of the proposed driving technique is application of asymmetric amplitude modulation of sustain pulses in the display period of the address, display-period separation (ADS) driving scheme. As a result, the range of luminance control by the proposed method is about 50% of the luminance for a given gray level. Moreover, it is experimentally verified that the proposed method has similar dynamic margin performances compared with the conventional method.     

LED点阵书写显示屏的设计

LED显示屏的设计硬件主要由STC89C58单片机最小系统、32×32的双色点阵显示阵列、光笔、按键、液晶显示屏等组成。双色点阵中的红色LED始终工作在微亮的扫描状态,STC89C58单片机利用自制的光笔中红外光电三极管检测光笔触及位置处红色LED灯的点亮,计算出光笔位置的行列坐标,并根据按键设置的不同工作模式控制LED显示,从而实现点亮、划亮、反显、清屏、笔画拖动、轮流显示等功能。显示屏能根据环境光强自动调节显示屏的显示亮度,当在设定时间内光笔未接触显示屏或按键未按下时关闭所有显示,并使系统进入休眠状态,减少电能消耗,当有按键按下时系统恢复运行。     

A 20-in. color DC gas-discharge panel for TV display

A 20-in. diagonal color gas-discharge panel with 640×448 cells and an average cell pitch of 0.65 mm has been experimentally developed using thick-film printing and photolithographic phosphor deposition techniques. Improvements in both the cell structure and fabrication technique have produced wide memory margins for the pulse memory operation. Full-size NTSC color TV pictures with excellent uniformity have been displayed with an area luminance of 17 fL and a luminous efficacy of 0.13 lm/W     

High-performance plasma display panel with cathodes in the cellwalls

An improved color DC plasma display structure was developed and its characteristics were investigated. The configuration of the device is formed using a multiple thick-film printing technique which allows the realization of a large-scale panel. Discharge occurs from thick cathodes formed on three of the cell sidewalls. The panel developed exhibits the following improvements when compared to a conventional panel with straight row-and-column electrodes: it generates a high luminous efficiency of 0.16 lm/W (a 1.3-fold improvement with a 200-μA/cell), produces high uniformity in light output (a 1.4-fold improvement), and has an increased lifetime under accelerated conditions of 240 h at 400 μA/cell (corresponding to a 4-fold improvement at 70% of initial brightness). The mechanisms of the improvements used in the new cathode structure are discussed     

Ultrahigh-speed photography of picosecond light pulses

A new technique for the display of picosecond light pulses is presented. Ultrashort (6 ps) green light pulses passing through a light-scattering medium are photographed from the side by a camera positioned behind a shutter of 10-ps framing time. The shutter is an ultrafast Kerr cell driven by infrared pulses 8 ps in duration. Color photographs show a bright spot on a dark background, revealing the unambiguous presence of well-isolated picosecond light pulses. The shape of the spot is the result of a convolution involving the three-dimensional shape of the green pulse and the time transmission function of the shutter, this function being dictated by the shape of the infrared pulse. The experiment indicates that a new technique for visualizing light pulses consists in simply observing their flight through a scattering medium from behind an ultrafast shutter having a framing time equal to the time resolution desired. The new technique has many advantages over the two-photon fluorescence display technique, such as higher sensitivity, wider spectral range, and easier interpretation. The ultrafast camera also can be used for the photographic measurement of ultrashort relaxation times in dielectrics and in fluorescent dyes.