Cheol Jang

Toward Flexible Transparent Plasma Display: Optical Characteristics of Low-Temperature Fabricated Organic-Based Display Structure

We report a flexible transparent display based on a plasma display platform. The test panel was designed to 42-in VGA resolution since the proposed flexible transparent plasma display is targeted for use in large-area and lightweight displays in order to replace windows. A test panel was fabricated with organic materials, with the exception of an electrode and the MgO protective layer. A polyethylene terephthalate (PET) plastic film was used as the substrate. The maximum temperature applied to PET substrates during the test panel fabrication was 60 °C. Each inner component had a high transparency of over 90%. The average transmittance of the test panel was 57.5% in the visible spectral range.

Improvement of Reliability of a Flexible Photoluminescent Display Using Organic-Based Materials

In this paper, a prototype flexible photoluminescent display using organic materials based on a low-temperature process, in which all steps are carried out at under 100 °C, is proposed and fabricated, and the results are compared with those of a conventional plasma display. The proposed flexible photoluminescent display showed a bending radius of about 5 cm, and microplasma was successfully generated in the panel with about 80 V of sustain margin, and similar characteristics compared with that of conventional plasma displays were observed. In addition, the reliability of the proposed display was evaluated over a long period of more than 30 h, which corresponds to a real operation time of 150 h, considering the acceleration factor, to assess its lifetime. Mechanisms for discharge gas contamination, which is a serious problem for reliability, were proposed, and various methods were suggested and applied to improve the reliability of the proposed display. From the continuous measurement of the luminance of test panels, it was found that the various methods suggested here yielded improved reliability of the proposed flexible photoluminescent displays. Thus, the proposed flexible photoluminescent display shows potential as a future flexible display.

Optical characteristics of YVO 4 :Eu 3+ phosphor in close proximity to Ag nanofilm: emitting layer for mirror-type displays

We demonstrate the optical characteristics of YVO4:Eu3+ phosphor in close proximity to Ag nanofilm to create a highly efficient emitting layer in mirror-type self-emissive displays. The propagating surface plasmon mode induced between the dielectric layer (MgO) and the Ag nanofilm activates the electric dipole transition of Eu3+ ions. The transmittance of a 100 nm-thick Ag nanofilm is zero in the visible wavelength range, making this nanofilm a good reflector in the visible wavelength range and capable of fulfilling a mirror function. The emission of an YVO4:Eu3+ phosphor layer with a 100 nm-thick Ag nanofilm was enhanced to the point that it was eight times higher than that of a reference sample without Ag nanofilm. Therefore, the present work shows potential for application to mirror-type displays with high luminous efficacy.

Flexible Photoluminescent Display Fabricated With Low-Temperature Process Using PET Substrates

A flexible photoluminescent display fabricated with a low-temperature process is proposed. The fabrication temperature is a critical issue because a flexible display requires a flexible plastic film as a substrate. New fabrication methods were devised for inner components consisting of a flexible photoluminescent display. Long-term observation was used to examine the reliability of components fabricated with newly adapted fabrication methods. The electrical properties of the test panel were also analyzed for characterization of the proposed flexible photoluminescent display. Microplasma inside the test panel was successfully generated when the test panel was bent. The results of this study confirm that the proposed flexible photoluminescent display structure has reasonable potential as a platform for large-area flexible display devices.

Study on Pulse Waveforms for Improving Voltage Margin and Luminous Efficacy in an AC Plasma Display Panel Having Auxiliary Electrodes

New pulse waveforms applied to an alternating-current plasma display panel (ac PDP) with an auxiliary electrode are investigated for the purpose of improving the panels operating voltage margin and luminous efficacy. In the proposed pulse waveforms with reciprocal sustain pulses, a pair of positive and negative sustain pulses is applied to the sustain electrodes simultaneously and alternately. A positive auxiliary pulse is applied to the auxiliary electrode immediately after reciprocal sustain pulses. The voltage margin becomes wider, and the luminous efficacy is improved because of the suppression of the discharge toward the address electrode. In the another proposed pulse waveforms with reciprocal sustain and auxiliary pulses, a negative pulse, which is the same as the negative pulse of reciprocal sustain pulses, is additionally applied to the auxiliary electrode when reciprocal sustain pulses are applied. This negative auxiliary pulse can maintain a high level of luminous efficacy because it supports the effect of the auxiliary pulses. The measurement results show that the operating voltage margin is about twice wider than that of the typical pulse waveforms for an ac PDP with an auxiliary electrode; furthermore, the maximum luminous efficacy is able to reach 3.14 lm/W in terms of the measurement of the discharge in a 50-in XGA resolution (0.27 mm × 0.81 mm) panel with a white cell and a gas mixture of Ne+20%Xe.

Driving Characteristics of a High-Efficacy AC PDP With an Auxiliary Electrode

A new driving waveform was proposed in order to stabilize the driving characteristics of a high-efficacy AC plasma-display panel (PDP) with a coplanar gap of 200 mum and an auxiliary electrode. To stabilize the reset and address discharge, an erase pulse was applied to the auxiliary electrode instead of the sustain electrode after the sustain period. The write pulse was applied to the scan electrode, and a reset discharge was induced between the scan and auxiliary electrodes. As a result, the minimum address voltage could be reduced to a level similar to that achieved with a conventional ac PDP with a coplanar gap of 80 mum. Furthermore, the address-discharge time lag of the ac PDP with a coplanar gap of 200 mum was improved to a level that is comparable with that of the ac PDP with a coplanar gap of 80 mum.

An Investigation of the Temporal Dark-Image-Sticking Phenomenon in an AC Plasma Display Panel With an Auxiliary Electrode

In this paper, the temporal dark-image-sticking phenomenon in an AC plasma display panel (PDP) with an auxiliary electrode is investigated. To investigate this phenomenon, temporal behaviors of a black background image were observed in accordance with the sustain-discharge time and the relaxation time. Since dark image sticking is related to the reset discharge, our measurements focused on the reset period. In the case of an ac PDP with three electrodes, iterant sustain discharges induced an increase in black luminance, thereby leaving a residual image. However, in the case of an AC PDP with an auxiliary electrode, there was no variation of luminance between the states before and after the iterant sustain discharges. As a result, no residual image remained, and no distortion of the image could be recognized with the human eye, even after iterant sustain discharges.

Improved discharge time lag of address pulse in an ACPDP with auxiliary electrodes

— New driving waveforms are proposed for an ACPDP with an auxiliary electrode. Auxiliary pulses and a stepped scan pulse during the address period distinguish the proposed waveforms from conventional waveforms. The address discharge time lag in an ACPDP with auxiliary electrodes was improved by application of auxiliary pulses and a stepped scan pulse during the address period. The interaction between the auxiliary pulse and the stepped scan pulse generates priming particles directly prior to the address discharge, and these priming particles influence the address discharge. As a result, the firing voltage of the address pulse is lowered, and the minimum address voltage is lower than that of conventional driving waveforms. Experimental results confirm that the address discharge time lag of the proposed waveforms is 32% lower than that of conventional driving waveforms.

Analysis of the driving characteristics for an ACPDP with an auxiliary electrode using the voltage-transfer closed surface

— The driving characteristics and wall-charge model of an ac plasma-display panel (ACPDP) with an auxiliary electrode were investigated by using voltage-transfer closed-surface modeling. To understand the wall-charge behavior of an ACPDP with an auxiliary electrode qualitatively, voltage-transfer closed-surface analysis was applied to a test panel under the full driving waveform. The voltage-transfer closed surfaces were obtained after the sustain, reset, and address periods, when the full-stage driving waveform was employed with the test panel. As a result, it was proven that the wall-charge model predicted in the previous work corresponded with the wall-charge behavior of an ACPDP with an auxiliary electrode. Also, based on the resultant form after the address period, the wall-charge model after the address period was recently added and the entire wall-charge model was completed in this work. In addition, by investigating the trajectory of the cell-state movement during the reset period, it was confirmed that the priming effect affected the reduced discharge time lag of an ACPDP with an auxiliary electrode under the newly proposed driving waveform for reducing address time lag.

P-138: Driving Waveforms for Reducing Address Discharge Time Lag in an AC PDP with Auxiliary Electrodes

The address discharge time lag in an AC PDP with auxiliary electrodes was improved by applying auxiliary pulses and a stepped scan pulse during the address period. Interaction between the auxiliary pulse and the stepped scan pulse generated priming particles during the address period, influencing the address discharge positively. As a result, the minimum address voltage was reduced, and was lower than that of conventional driving waveforms. Furthermore, when the proposed waveforms were applied, the address discharge time lag was improved by 32% compared to that of the conventional driving waveforms with the same address voltage.