Philips Journal of Research最新文献

The construction of a Zeus panel is discussed. This type of panel has a relatively simple self-aligned construction with a limited number of different components. Due to the low number of connections, rather robust connectors can be used. The complete physical processing cycle, very important for this type of panel, can be as short as 3 h which is shorter than the processing of a standard CRT.

Pay television (pay TV) systems are presented as they are envisaged in the near future when broadcasters will switch over from analogue to digital transmission formats. Special attention is given to the standardization of pay TV systems by the DVB standardization organization. Philips firmly believes in standardization and aims at a high level of commonality at both ends of the transmission channel. This will reduce the price of the equipment, especially the decoders, and also facilitate interaction with studio equipment supplied by other manufacturers. The standardization is all the more important since we are on the verge of the new digital transmission era in which the consumer will be confronted with a wide range of new services.

Although in a Zeus display a straightforward matrix addressing system can be constructed from just vertical electron-transport channels and horizontal row extraction electrodes, there are many unique advantages in adding extra selection plates. These are, e.g. cost reduction by a trade-off between electronics complexity and panel complexity, enhancement of internal contrast and, by choosing wider channels, reduction of transport voltage and improvement of triode performance. Several implications for the system design are discussed. Some subtle effects in the physics of selection switches are explained together with design rules for the selection plate geometry that avoid the associated image artefacts.

In a Zeus display hopping electrons are transported through channels with extraction holes. If a sufficient transport field is applied, the electrons hop low and leakage through the holes is negligible. The electrons can be extracted from the channel by applying a positive voltage pulse to an extraction electrode. With sufficient pulse amplitude the extraction efficiency is 100 %, independent of small variations in material properties, which enables the creation of uniform images. Experiments on a model transport channel confirm the mechanisms behind transport and extraction.

We introduce the transmission system selected for the next generation of North American broadcast television and for high data rate transmission on cable TV systems. We describe key features of the digital vestigial sideband (VSB) modulation and error protection employed in this system, and of the quadrature amplitude modulation (QAM) systems that competed against it for selection. We review the process used to select this system, in addition to the criteria by which the selection was made. We further review the performance of the system under actual field conditions. The 8-VSB terrestrial mode was found to perform better than the existing NTSC broadcasting system. The 16-VSB high data rate cable mode was found to perform essentially error-free at all receiving locations that met Federal Communications Commission (FCC) specifications for carrier-to-noise ratio.

In the Zeus display panel, as in other flat-panel cathode ray tubes, the anode voltage is limited to a few kV. The effects of the anode voltage on phosphor screen performance are discussed which include energy conversion loss processes at the phosphor surface and variation of the number of luminescent centres available. Phosphor efficiency saturation has been measured in the range of 1 to 10 kV, using a pulse-width-modulation scheme. The luminance performance at different excitation conditions is predicted and confirmed experimentally.

Coulomb degradation of phosphor screens is shown to increase with decreasing anode voltage. Novel ultra-thin and dense anti-degradation coatings have been developed for zinc sulphide phosphors which effectively prevent fast degradation due to chemical surface reactions. In this way a satisfactory solution has been found to obtain in the Zeus display a luminance level about equal to the best conventional tubes.

Digital video transmission over satellite channels is described. Many systems have so far been proposed for satellite transmission, and exist in some form. Recently, the European Telecommunications Standard (ETS 300 421) has now been accepted by the Digital Audio-Video Interface Council (DAVIC) as the world standard. In the following, we describe the ETS 300 421 or the DVB-S (Digital Video Broadcasting-Satellite) standard. Specifically, the rationale for the selection of different parameters of the DVB-S standard is explained. Performance of the DVB-S system for a representative case is submitted. Finally, receiver performance issues are addressed.

Developments in video compression and VLSI technologies are producing revolutionary changes in the television industry. Television signals worldwide are beginning to be compressed, encoded and transmitted using digital means. Using digital compression, encoding and transmission techniques has the advantage of better bandwidth utilization, flexibility and ease of integration with other digital data, and an overall higher quality of video at the receiver. The purpose of this paper is two-fold. Firstly, an introduction to video compression in the context of emerging digital television standards is provided. The important role played by International Standards, specifically MPEG, in the development of digital television systems is discussed. Secondly, current trends in the use of compression in the development of digital television for deployment in the United States and Europe, and the participation of Philips in these new applications, are discussed.