Jae-Chul Jung

Electro-optic characteristics and areal selective dimming method for a new highly efficient mercury-free flat fluorescent lamp (MFFL)

A highly efficient mercury-free flat fluorescent lamp (MFFL) with dielectric barrier Xe gas discharge was developed for a LCD-TV backlight source. The unit cell of the lamp has a simple structure with two main electrodes running parallel to each other and an auxiliary electrode. The adoption of the auxiliary electrode resulted in a wide, stable operating voltage margin, high luminance and efficiency. The 4 inch diagonal size lamp showed a luminous efficacy of 44 lm W−1 at a luminance of 3400 cd m−2 with Ne–Xe(18%) gas mixture. We demonstrated that the 4 inch unit cell can be used to construct a 5 × 8 multi-structured lamp of 32 inch diagonal size for application in a large-sized LCD backlight source by a simple repeat of the unit cell. Despite the increase in size, the 32 inch lamp showed the same discharge voltage and margin of the 4 inch unit cell. Using the proposed MFFL with the auxiliary electrode as the data electrode and the subfield method, we developed a driving scheme for 2-bit areal selective dimming control of an M × N multi-cell lamp which can be operated using only one inverter.

Improvement of Luminance and Luminous Efficacy of Mercury-Free, Flat Fluorescent Lamp by Optimizing Phosphor Profile

A highly efficient mercury-free fluorescent lamp (MFFL) was developed for an alternative to fluorescent lamps containing mercury. The lamp has a simple structure with two main electrodes running parallel to each other and an auxiliary electrode. In order to improve the luminance and luminous efficacy of MFFLs further, we optimized the thickness of rear and front phosphors on the inner surfaces of the lamp, and then adopted an uneven distribution profile for the rear phosphor to increase the surface area of the phosphor. The MFFL with the optimized phosphor profile showed a wide luminance range from 3315 to 17133 cd/m2 with the corresponding luminous efficacy from 75.2 to 42.5 lm/W with the color coordinate around (0.32, 0.32) for daylight.

38.2: The Electro-Optic Characteristics of MFFL (Mercury-Free Flat Fluorescent Lamp) for LCD Backlighting

In this work, we have studied the electro-optic characteristics of multi-cell structured, highly efficient Mercury-free Flat Fluorescent Lamp (MFFL). It was found that each cell of the newly suggested multi-cell structured MFFL could be operated independently by the pulse amplitude modulation, and/or pulse width and/or frequency modulation method which can be utilized to make a back light source for LCD with an areal dimming capability. A wide driving voltage margin of stable glow enabled to have a large luminance variation which resulted in the dimming ratio of 14%, while the frequency and the pulse width modulation resulted in the dimming ratio of 25 and 31% respectively. The interconnection of multi-cell structured MFFL for the full size LCD together with its driving wave form for the independent operation of each cell with a 4 bit sub-field method and its consequent 16 level lighting for each TV field are suggested.

High-Speed Reset Waveform for PDP With Erase Address Discharge

We propose a new high-speed reset waveform which uses a negatively biased voltage to the common electrode and an alternating ramp voltage to the scan electrode during the reset period and an erase address scheme. It showed a less than 800-ns time lag, a wide address margin over 40 V, and improved jitter characteristics among different color cells in a plasma display panel with a 50-in full-high-definition resolution. Its fast discharge characteristics were attributed to the formation of a higher wall voltage near the middle of the gap during the reset period and the consequent bigger electric field during the scan period which was confirmed by the 3-D emission observation and cell-voltage-domain analysis.

Adaptive Local Dimming Lighting of Mercury-Free Flat Fluorescent Lamp Using Dual Auxiliary Electrode

A new drive method designed for the adaptive local dimming lighting of a multistructured 32-in diagonal-sized mercury-free flat fluorescent lamp (MFFL) which consists of a matrix array of 10 × 16 60-mm diagonal-sized unit cells is proposed. The adoption of the dual auxiliary electrode and the bipolar-pulse drive scheme resulted in a wide stable operating voltage margin at low driving voltages. The cell turn-on or turn-off selectivity can be obtained through the change of the connection state of the dual electrode. Using the proposed MFFL with the dual auxiliary electrode as a data electrode and the subfield method, a new drive scheme for a 2-b adaptive local dimming control of 10 × 16 lamp array with one inverter system is proposed and demonstrated.

High-luminance and luminous-efficacy mercury-free flat fluorescent lamp (MFFL) with local-dimming functionality

— In order to realize high-luminance and luminous-efficacy mercury-free flat fluorescent lamps (MFFLs) for LCD backlighting, the phosphor profile was optimized to enlarge the surface area. The proposed uneven profile of the rear phosphor increases the effective surface area of the phosphor, resulting in a wide luminance range from 3000 to 16,788 cd/m2 with a corresponding high luminous efficacy from 66 to 34.7 lm/W, respectively. Also, a dynamic operation method for an adaptive local-dimming and scanning operation is proposed which can be used in a 32-in. multi-structured configuration having one inverter system. With the deployment of the bipolar drive scheme and dual auxiliary electrodes, a stable and selective diffuse glow discharge with high luminance is possible.

The dependence of the thermal characteristics variation and image sticking phenomenon of PDP on the dielectric loss

Abstract The discharge condition of Plasma Display Panel (PDP) changes as the operating time increases. Imaginary part of permittivity of dielectric material which is related to the dielectric loss has been often neglected because of the relatively small values compare to that of the real part. However we have found that some aspect of the long term behavior of PDP is closely related to the dielectric losses. We have studied and compared the thermal characteristics variation and temporal image sticking phenomenon of PDP with two different kinds of dielectrics and correlated with the dielectric losses.

The effect of self-erase discharge on the luminous efficacy of alternating current plasma display panels

In this work, we studied the effect of self-erase discharge on the luminous efficacy of alternating current plasma display panels. Through discharge current analysis, we observed that self-erase discharge occurred mainly between the sustain cathode and the address electrode, which has an influence on the luminous efficacy. We varied the amount and timing of the self-erase discharge in order to observe the effects on the luminous efficacy. We found that the luminous efficacy could be improved by a self-erase discharge when adjusted to occur right before the main discharge in the small gap structure. In the long gap structure, on the contrary, we could increase the luminous efficacy when we suppressed the self-erase discharge. In addition, we suggest various waveforms to control self-erase discharge as a result of our panel experiments.

New Address-While-Display Driving Method for High Contrast Ratio and Wide Operation Margin PDP Using Short Ramp Reset (SRR) and Short Pulse Erase (SPE) Schemes

We propose a new address-while-display (AWD) driving method for a plasma display panel to obtain a high contrast ratio and a wide operation margin, which is composed of a short ramp reset (SRR) period, a short erase period, a sustain period, and an address period as the basic units. The SRR pulse and the short pulse erase period make it possible to obtain a wide operating voltage margin and minimize the background luminance by redistributing the wall charges in a short initialization time between the address and the scan electrode. As a result, a high darkroom contrast ratio of 10 000 :1 could be achieved with a wide operating voltage margin of 40 V for a stable address.