Hyoungsik Nam

18.1: Distinguished Paper: Novel TFT‐LCD Technology for Motion Blur Reduction Using 120Hz Driving with McFi

Samsung has launched a 70-inch Full HD (1920×1080) LCD-TV panel which, on a commercial basis, is the worlds largest size so far. This size is the maximum that can be achieved using a single polarizer sheet. Its features include 600 nits luminance, dynamic control using LED local dimming, 100,000:1 contrast ratio, and a color gamut of 105%. Also, it is the worlds first high speed FHD 120Hz frame rate panel, accompanied by a newly developed pixel structure and driving scheme. This totally new driving method concept includes an alternative pixel structure developed from the 1G-2D cell structure that we announced last year. Also, new product and design technology, optimized for larger sized LCD-TV products, was adopted. This technology overcomes severe charging margin requirements, enabling manufacturability and high quality in Samsungs FHD line-up (40″, 46″, 52″, 57″, 70″).

43.3: Distinguished Paper: An Advanced Intra‐Panel Interface (AiPi) with Clock Embedded Multi‐Level Point‐to‐Point Differential Signaling for Large‐Sized TFT‐LCD Applications

In this paper, we present the newly developed intra-panel interface targeting to replace conventional multi-drop bus architecture with point-to-point differential interface. The multi-level signaling scheme is adopted to remove separate clock and control signal lines by embedding clock information into multi-level signal. The clock embedding scheme removes the skew problem found in previously announced intra-panel interface, and provides lower EMI. The simple multi-level signal detector is used to regenerate the clock signal from the data stream and does not require any sophisticated clock recovery unit in the receiver. The AiPi can be an effective solution to large size TFT LCD applications due to the reduced signal lines, lower EMI, and lower power consumption.

CCFL backlight solution for low-cost liquid crystal televisions without image artifacts

Recently, a single-phase CCFL (cold cathode fluorescent lamp) driving method has been adopted to provide a low cost implementation. However, whereas dual-phase driving compensates the coupling effect on the pixel electrodes, single-phase high voltage driving signals are coupled to pixel electrodes through parasitic capacitance between the lamps and panel electrodes. As a result, image artifacts appear on the display screen. This paper describes the analysis results of this phenomenon. Furthermore, the proposed automatic delay compensation scheme eliminates the artifacts caused by the coupling effect, regardless of how much delay is generated by the lamp driving circuit.

Analytic solution to remove flickers on a liquid crystal display television

Flickers have been critical issues on liquid crystal displays (LCDs) which use a backlight unit (BLU) under a panel. The luminance modulation of the backlight and the transmittance of the panel are independently investigated in frequency domain to look for an analytic solution to remove flickers on the LCD panel. The transmittance of the panel depends on how to drive the LC molecules and how the LC molecules respond. We shows there are three frequency components caused by only the panel driving. It is shown that the flicker can be generated by the inter-modulation effect between two different frequency groups from the BLU and the panel. To remove flickers on LCD TV panels, the frequency of the PWM backlight signal should be carefully chosen so that the inter-modulation frequencies may be higher than 60 Hz. It is shown that it is impossible to perceive flickers on an LCDTV operating at 120 Hz refresh rate if the frequency of the PWM signal is 120 Hz or 180 Hz.

Analysis of response‐time compensation for black‐frame insertion

— An impulsive driving technique has been widely adopted for the elimination of motion blur in LCDs. Although the problem of slow temporal response time is very well known for LCDs, the inherent motion blur of moving objects in hold-type displays has a more-serious impact on display performance. It is well known that even very fast LCDs with zero response time still suffer from the motion-blur artifact due to hold-type driving effects. However, a fast temporal response is also critical in order to maximize the blur-reduction effect even in the case of impulsive driving. In this paper, the special behavior of LC molecules in an impulsive driving environment has been analyzed especially for the case of black-frame insertion, and we propose an effective means to implement optimized response-time compensation (RTC) for the black-frame insertion technique.

45.3: Cost Effective 60Hz FHD LCD with 800Mbps AiPi Technology

AiPi technology incorporates an embedded clock and control scheme with a point-to-point bus topology, achieving the smallest possible number of interface lines between a timing controller and source drivers. A point-to-point architecture enables the data rate to be boosted and the number of interface lines to be reduced because impedance matching can be easily achieved. An embedded clock and control scheme is implemented by means of multi-level signaling resulting in simple clock/data recovery circuitry. A 46″ AiPi-based 10-bit FHD prototype requires only 20 interface lines, compared to 38 lines for mini-LVDS. The measured maximum data rate per one data pair is more than 800Mbps.

A cost‐effective 60hz FHD LCD using 800Mbps AiPi technology

Abstract AiPi technology incorporates an embedded clock and control scheme with a point‐to‐point bus topology, thereby having the smallest possible number of interface lines between a timing controller and column drivers. A point‐to‐point architecture boosts the data rate and reduces the number of interface lines, because impedance matching can be easily achieved. An embedded clock and control scheme is implemented by means of multi‐level signalling, which results in a simple clock/data recovery circuitry. A 46” AiPi‐based 10‐bit FHD prototype requires only 20 interface lines, compared to 38 lines for mini‐LVDS. The measured maximum data rate per data pair is more than 800 Mbps.

Dithering artifacts in liquid crystal displays and analytic solution to avoid them

Dithering is a bit-extension technique that has been used in various areas of gamma correction, picture quality improvement, viewing angle enhancement, high dynamic range (HDR) liquid crystal display (LCD) televisions. This technology generates intermediate levels between neighboring grays by displaying the neighboring grays according to predefined data sequence of pixels. However, the predefined data arrangement can cause some artifacts such as flicker, vertical and horizontal line artifacts. This paper reports dithering artifacts on LCD screens for the first time in the literature. We analyze why the artifacts take place and propose new dithering data arrangements to avoid the artifacts by taking account of polarities of pixels.

Novel impulsive driving schemes for 120Hz LCD panels

Abstract Two new impulsive driving technologies for 120Hz liquid crystal display (LCD) panels are proposed to improve moving picture quality. One technology generates the dark frame using an adder and a shifter simply without using any look up tables (LUTs). It results in a cost effective impulsive scheme with motion picture quality comparable to that of high speed driving. The other is a backlight flashing method designed to avoid ghost images. The issue of ghost images caused by the slow response time of liquid crystal (LC) is solved by means of 120Hz overdriving and 120Hz backlight flashing. Using the perceived blur edge time (PBET) metric, measured moving picture response time (MPRT) values were 10.8ms and 4.4ms, respectively, while that of 120Hz high speed driving was 10.1ms.

22.1: Low Power Driving Scheme for High Frame Rate LCD TVs

Recently, there have been lots of demands for green products. One of solutions is to reduce the power consumption. Whereas the most approaches in liquid crystal displays (LCDs) are focused on reduction of the backlight power consumption with local dimming technologies, this paper proposes the new low power driving scheme for LCD TV panels operated at high frame rates of 120Hz and 240Hz. Dynamic and static power consumptions have been lowered by means of the frame rate reduction for still input image and fallback and the charge sharing method applied at the vertical blank period. As the maximum, the total power can be reduced to around 50% and 75% for 120Hz and 240Hz.