The aim of this paper is to evaluate stability of low-temperature fusing toner and to give a brief comparison with the emulsion aggregation(EA)toner in order to be applied to as the toner of electrophotographic system on the condition of a low temperature. DSC and TGA measurements were tested. Flow measurements were carried out three or four kinds of toners in order to clarify some of their rheological characteristics. The influence of temperature and especially the effect of melamine wall were examined. Also fluidity tests of sample toners were conducted. In this study, it is seen that micro-encapsulation is useful method to prevent an aggregation between toners. It is found out that micro-encapsulated toner(MC toner)have a higher magnitude of G' and/or tan F4 than that of EA toner. Because melamine wall of MC toner is easy to show an elastic properties compare with EA toner over the frequency and strain range. MC toner shows a good result on the fluidity test as well.
The stability of the corona discharge is a significant factor in electrophotographic process. In this study, the influences of the relative humidity and temperature on the corona discharge and the characteristics of the initial behavior of the corona discharge are investigated. The voltage for maintaining corona current constant is monitored as a function of time. When the relative humidity increases, the voltage increase is observed on both polarity cases. The decrease of the ion mobility is considered to be the main factor to disturb the corona discharge. The corona discharge is promoted by the increase of the temperature. It is considered that the ionization is promoted in the both polarity cases. In the initial behavior of the corona discharges, the voltage decrease is observed in the positive case, and the voltage increase is observed in the negative case. From the voltage change, the mechanisms of the initial behavior of the corona discharge are considered as the promotion caused by the rise of the temperature of the discharge plasma area and the suppression by the generation of the ozone.
Improvements in the control of toner adhesion over the last 50 years have been essential elements in the inventions of new electrophotographic development systems. These new development systems led to customer-perceived, step-function improvements in copiers and laser printers. Projections for the future of electrophotography for the next 50 years can be made based on the assumption of continued improvements in toner adhesion control.
The liquid crystal display (LCD) has replaced the desktop monitor that was the main market of cathode ray tube (CRT), and even a TV use enlarges the market share. The LCD using in plane switching (IPS) technology has overcome the inherent difficulty of narrow viewing angle performance of the conventional LCD. In this paper, the history of IPS is clarified, and then the viewing angle characteristics and moving picture performance of IPS panel are explained.
Recently wide color gamut technologies of liquid crystal displays are proposed in two ways. One is LED backlight technology and the other is multi primary color technology that has more than 3 sub pixels. In this research we evaluate these technologies by comparing color gamut with real surface colors(Pointer's dataset). At first we show LED backlight LCD can reproduce almost all Pointers' dataset. We can say that LED backlight LCD has excellent color gamut in 3 primary color systems. Furthermore we propose RGBYC 5 primary color display. We show the RGBYC 5 primary color display is one of the most efficient methods to include the entire gamut of the real surface colors. RGBYC 5 primary color display is the up-and-coming technology as well as the LED backlight LCD.
Organic light emitting diode(OLED)display emits by itself and is expected to become a display with the potentiality of high quality image, ultra-slim, light-weight, and low power consumption. Although it had been utilized for automobile displays or mobile displays, SONY pioneered the TV use by launching an 11-inch OLED television(XEL-1)in November 2007. This paper introduces some techniques we have developed for OLED displays and the excellent performance of their image quality, and also introduces techniques we are developing now for the future OLED displays of large size
OLED(Organic Light Emitting Diode), that has been expected as the next generation standard of FPD(Flat Panel Display), has excellent characteristics of wide color gamut, high contrast ratio of more than 1 million to 1, very fast response time and wide viewing angle, and it realizes very thin display module because of no need of backlight system. However, there are three critical problems that OLED must overcome to compete with LCD. First, TFT backplane technology for large glass substrate is required. The TFT must be stable enough and fabrication process must be simple. Second, OLED pattering technology for large glass substrate must be developed. Third, OLED driving technology must be improved to maximize OLED performance and to increase lifetime of the products. This paper will review the newest development trend of OLED technologies in Korea to overcome the above three problems and also to create new applications.
Launching of the first 42-inch TV sets, featuring Plasma Display Panel (PDP) by Japanese manufacturers in late 1990s, has set off the age of Flat Panel Display (FPD) as we are experiencing today. As a result of constant reduction in cost and strenuous efforts to realize larger sizes, plasma display and LCD have become dominant devices in the market. This paper reviews recent progress in image quality and improvement of overall performance through the development of plasma display. New approaches inspired by the development of devices in order to evaluate image quality of displays as close as possible to human perception, are also covered.
Flexible displays recently attract a great deal of attention as next-generation technology to create various electronic display styles. We have been developing organic light emitting diodes (OLEDs), liquid crystal (LC) devices, organic thin film transistors (OTFTs) on plastic substrates, to realize a flexible thin light-weight display for moving images. In flexible OLED devices, phosphorescent polymers were introduced into light emitting layers with high efficiency. In flexible LC devices, a fast-response LC/polymer composite film was formed to keep substrate gap constant. To drive these display devices, we also fabricated low-voltage OTFT array on the plastic substrate. We have demonstrated flexible color active-matrix displays of OLED and LC based on the OTFT technology.