Jae-won Lee

68.1: Capacitance‐Voltage Characteristics of Top Emitting Organic Light Emitting Diodes for Mobile Display Application

In this paper, Capacitance-Voltage (CV) measurements as a powerful technique to analyze electric properties of Top emitting OLED (TOLED) devices are introduced. After comparing CV characteristics between inverted TOLED and conventional TOLED with thin metal, it is found that inverted OLED struggles charge injection, especially electron injection. Here Current-Voltage-Luminance (IVL) and CV characteristics are carefully analyzed for single carrier devices and dual carrier devices systematically. Top emitting OLED (TOLED) with thin metal cathode shows more efficient electron injection and higher efficiency than that of inverted OLED, which is attributed to the order of thermal deposition of organic/metal layers.

P‐87: Local Dimming Design and Optimization for Edge‐Type LED Backlight Unit

As the LCD TV market expands, the demands for a high-performance, high-definition image quality and eco-friendly products are constantly rising. The LED backlight technology is a primary case which satisfies such demands. The LED backlight can be classified as either a direct-type or an edge-type according to the arrangement of light sources. The direct-type has advantage of 2-dimensional dimming leading to a low power consumption and better image quality whereas edge-type has advantage in the fancy design, achieving slim thickness. To achieve the slim design and the low power consumption, the edge-type backlight unit is preferred to direct-type. A new type of edge backlight structure is proposed with edge local dimming to achieve higher Contrast Ratio (C/R) and low power consumption in addition to the advantage of a slim thickness. A new Light Guide Plate (LGP) structure for edge local dimming was verified and lenticular LGP is proposed to obtain straight line motion of light. In addition, power consumption reduction was achieved though algorithm development. A patterned LGP production method of various concepts was examined to realize 2-line local dimming. It was reduced 30% power consumption of all energy through 2-line local dimming structure. And, CR improved with 14,500:1 from 1, 128:1.

Investigation of the interaction between rubbing cloth and pattern structure on in‐plane‐switching liquid‐crystal displays

— For the rubbing process, there have been several problems, especially scratching, disclination, and light leakage that increases the black luminance of a panel because the alignment of the liquid crystals might not be uniform due to a fluctuation in the fine-rubbing direction. To investigate the basic causes of these problems, several experiments concerning the characteristics of the rubbing cloth and the pattern structures on an LCD substrate were carried out. A new mechanism regarding the interaction between the rotation of filaments on the rubbing cloth and the structure of patterns on the IPS-LCD substrate is proposed. There is a correlation between the filaments rubbing direction and the pattern angle of the substrate. A new rubbing method based on two types of rubbing cloths were introduced to improve the rubbing density. As a result, it was determined that the black luminance was relatively reduced by using this method compared with that of conventional rubbing processes.

54.2: Bidirectional LCD Monitor using Single Backlight Unit

Recently, as LCD (Liquid Crystal Display) monitors have been widely used in public places such as banks, hospitals, counseling offices, wholesale marts and theaters, there is an increasing demand on their function of mutual communication. Since the conventional 2D displays can be observed only in front of the displaying side, two-way communication was achieved by spatial configuration of two or more monitors. This is not an efficient way in aspects of power consumption, space occupation and costs. Therefore, in this paper, the bidirectional LCD module with edge-lit BLU (Backlight Unit) is proposed by utilizing LGP (Light Guide Plate) patterning technology, with a single BLU for simultaneous display. In particular, 40 % reduction in thickness, 15 % decreased power consumption, and 13.8 % of lower production cost is achieved when compared with a conventional bidirectional display.

Compatibility of Micro Lens Film and Circular Polarizer on Bottom emitting OLED display

We demonstrated a 42% luminance enhancement by attaching MLF (Micro Lens Film) on the bottom emitting OLED. Higher density of MLF extracted more substrate mode to air. We also investigated the compatibility of MLF and Circular Polarizer (CP) on the bottom emitting OLED. It is found that the efficiency of bottom emitting OLED with MLF and CP decreases comparing to the reference OLED device, which has CP alone. Simulation shows that large portion of light is reflected back into CP at the surface of MLF and air. Back reflected light from MLF is absorbed in CP layer. We have also shown that OLED blur image be enhanced by reducing substrate thickness.

P‐86: Collimation Sheet Design for the One‐Side Edge‐Lit Backlight

Collimation sheet for the edge-lit backlight has been designed, which is well specialized for the emission profile of one-side edge-lit backlight. Operation theory and design principles of the proposed sheet were presented in detail. Simulation study shows that emission angle of 12° is achievable using the designed sheet without additional sheets while conventional backlight has the angle of 50° with two sheets (micro lens sheet and prism sheet).

42.3: Investigation of Interaction between Rubbing Cloth and Pattern Structure on the In-Plane-Switching Liquid Crystal Displays

We proposed a new mechanism of interaction between rotation of filaments in the rubbing cloth and structure of patterns on the substrate. Using this mechanism, we introduced a new method of rubbing which uses two kinds of rubbing cloths to improve the rubbing density. And we obtained that black luminance decrease.