State-of-the-art display devices are reviewed. The operation mechanism of individual display technology and the evaluation items are described. For the breakthrough in the research and development of display technologies of the new era, approaches from various fields of surface science are needed and expected.
Computer users often suffer heavy work loads seeing display devices, because they have to gaze on the bright and small characters and complex figures displayed with high density and high resolution at relatively close distances. Therefore, there are many problems on human factors we have to consider in designing display devices. This article introduces several basic problems covering the relationship between visual effects and display device characteristics such as the spatial frequency response of devices, brightness, contrast and color of displayed images. Furthermore, problems relating visual fatigue are analysed and methods to reduce them are described.
Devices for non-active matrix addressed liquid crystal displays and their substrate surface treatments are reviewed. Liquid crystal interfacial alignment with a high pretilt angle is needed for the display panels with large information contents. This is being achieved by substrate surface treatments utilizing selected polyimide coating materials and a controlled surface rubbing technique. For the further improvement of the technology, controlling both interfacial liquid crystal molecular alignment angle and its anchoring strength, is strongly required.
Elctrochromic materials and thin film formation techniques are reviewed. Transition metal oxides, such as WO3, MoO3, NiOOH, and IrOx are chemically or electrochemically filmed on ITO glasses. These methods can be used for the large scale production of the desplay surface. In the case of organic materials, viologens are the most comonly used. During repeated coloration and bleaching, these materials are, however, easily converted into irreversible species. This is stabilized by clusrate formation with cyclodextrin. Anodic polymerization of aniline or pyrole is of alternate possibillity of the organic electrochromic materials. Since the ECD is one of the electrochemical cells, the two electrodes and electrolyte between them are the basic components. Therefore, the selection of the electrolyte is of great importance, as well as the selection of the elctrochromic materials. Finally the merit and demerit of the ECD are described.
In this article, the fundamental concept and structure of reflective and transmissive ECD's are reviewed. Various types of ECD's such as large-scale or solid-state ECD's are describedin terms of their performances. In the discussion it is concluded that the response of large-scale or solid-state ECD's is reduced primarily due to the presence of resistivity of TCO. Finally some possibility of large-scale and solid-state ECD's is discussed with a prospective materials survey.
Since a mass production of a large 37″ CRT was achieved in 1984, 41″, 42″, 32″, 43″, 33″ and 45″ CRTs were successively developed by CRT manufacturers in Japan for three years. This paper reviews the engineering and technical subjects in the mass production of large CRTs, such as glass bulbs, shadow masks, phosphor screens, electron guns, color purity under terrestrial magnetism, and manufacturing processes. Among them, glass bulbs are discussed in detail.
There are several problems to be resolved to improve resolution and flatness of the CRT. A larger caliber lens and/or a multiplex lens are introduced in an electron gun to achieve smaller and sharper beam spot size. Corrections by quadrupole and/or DY (Deflection Yoke) with reactors are applied to imporove beam distortion. There are also difficult problems in negatives, materials, and accuracy in etching processes for mask fabrication. Decreasing power loss, improving response in transient, convergence, and raster distortion are other objects associated with DY. This paper describes the current status for above items and some approaches to resolve and overcome them.
Recently, the electroluminescent (EL) technology has made a great progress in developing multi-color panels. In this paper, first, both AC and DC ZnS electroluminescent display devices having powder or thin film structures are reviewed, and their properties and characteristics are discussed. Secondly, the present fabrication techniques are outlined, and finally, the state of the arts in the electroluminescent display devices and its future trends also are discussed.
Efforts have been paid to improve the performance of thin-film electroluminescent (EL) devices because of their high potential to be used in the field of a large area displays. EL devices have such advantages as solid-state emissive-type display, a capability of high density integrations and a low power dissipation. This article reviews the rapid progress for the last several years in materials, film growth methods, and device construction technologies for multi-color thin-film EL panels.
The drive methods for TF-EL displays were, so far, field refresh and p-n symmetric drive methods. We have developed a new bi-directional push-pull symmetric drive method in order to grade up the display ability by increasing display capacity, decreasing power consumption and reducing the unit cost. The circuit construction, specifications of high voltage driver IC, driving method, and 640×400 dots TF-EL display driven by this drive method are described.
The development of high-brightness GaP (green) and GaAlAs (red) LEDs has brought about greatly expanded LED applications to flat panel display devices. Since a low-cost production process for monolithic devices is now available, the display devices are expected to be used soon in automobile displays. Hybrid devices such as outdoor traffic information signs and billboards are seen in a number of new applications. The next important step is to develop a bright blue LED for flat panel display devices. This paper presents new trends in the LED technology.
Plasma display panels (PDPs) have been developed so far mainly for office automation. In the past several years, 640×400-dot PDPs, corresponding to 12-inch-diagonal monochrome CRTs, have been put on the market by various manufactures as very thin display units containing integrated drive circuits. On the ohte hand, research and development on the color PDP have been being carried out to realize the color PDPs for graphic displays and flat large-size color TV receivers. This paper discribes both the principles of the monochrome PDPs on the market and the present status of color-PDP research.
The Vacuum Fluorescent Display (VFD), a kind of triode electron tube, has been in the market for 21 years since it was developed first. The first feature was of a 7 segmented type and then a variety of types, 5×7 dot character type, dot matrix type, complex-pattern type, etc. were successively developed in the sequence. Today, ultra-small active-matrix VFDs using MOSFET substrates are under development. The low voltage drive is known as a distinctive feature of VFDs. However the emission color of all early VFDs was limited to blue-green only. The current VFDs are enable to emit almost all colors, such as red, orange, lemon and etc.. Thus VFDs have taken place of other display devices and occupies an important position. Problems for future VFDs developing highly efficient phosphors that can emit multi-color, fabrication of the high resolution phosphor screens, elimination of the vacuum exhaust tube, etc. are pointed out.
Zinc pyrithione has been proved an effective anti-dandruff agent. Several types of medicated shampoos contai ning this compound are sold and have been at the top share in the market in Japan. Ultra fine particles of zinc pyrithione were developed to prevent their sedimentation in the shampoo formula. A stable dispersion in concentrated detergent solutions was achieved by treating the powder surface with polymers. As compared to the commercial zinc pyrithion, the ultra fine particles of zinc pyrition in the shampoo formula showed a larger amount of and a higher rate of adsorption onto the human hair and the mouse skin. But it showed the same percutaneous absorption into the rat skin as commercial zinc pyrithion.