Philips Journal of Research最新文献

A high voltage is applied to the screen spacer of the Zeus panel to obtain high brightness and long phosphor lifetime. To prevent field emission due to high local field strength, the screen spacer is coated with a resistivity layer and a low secondary-electron-emission layer. Efficiently operating panels have been made with sputtered substoichiometric and stoichiometric silicon nitride films, and with sprayed chromium oxide and silicon nitride particle layers. For the sputtered layers the effect of stoichiometry, sheet resistance and layer thickness on the panel performance is discussed. In the case of the sprayed layers the effect of suspension quality, spray conditions, layer thickness and layer roughness is discussed.

Thin layers of MgO are applied in the Zeus panel to tower the field strength needed for electron transport. The layers can be applied by evaporation or spray pyrolysis. To achieve proper performance the layers should be smooth and at least 40 nm thick. MgO is easily degraded upon storage in air by the formation of a surface layer of magnesium carbonate and magnesium hydroxide. However, heating the contaminated layer briefly at a temperature of 450 °C in air is sufficient to regenerate the MgO surface.

Metallization patterns are applied to the selection plates of the Zeus panel to be able to direct the electrons through the substructure to the proper colour pixel at the phosphor screen. The patterns, which also partially cover the insides of the holes in the selection plates, are applied using a subtractive process with either vacuum-deposited aluminium or wet-chemically applied silver. Different options for the lithographic resist are discussed, i.e. a cataphoretic negative resist and a sprayed positive resist. Satisfactory results have been obtained with both options. Adhesion of the metal to glass has been accomplished by application of a chromium adhesion layer in the case of the vacuum-deposited metal and by mechanical anchoring in the case of the wet-chemically applied metallization.

This paper presents the basic hardware and software architecture of a class of multi-media terminals that are connected to networks which deliver entertainment and home shopping services to consumers. Some important attributes of the multi-media terminal are: simple user input devices (e.g. infrared remote control), real-time interactivity, adherence to international standards for information representation and communication, and support for downloaded applications from service providers. The terminal discussed in this paper is representative of the current offering of the Digital Video Communication Systems (DVS) business unit of Philips. These terminals are the result of close cooperation between research and product divisions of Philips world-wide in the race to compete in the rapidly growing multi-media and communications markets. The current architecture of the terminal reflects the urgency to get to market with a viable solution; therefore the paper gives some indication of future trends for the hardware and software architecture for this class of multi-media terminals.

The emerging technologies of digital video and high-speed networks are combined together in a set-top box to provide a wide variety of value-added services to consumers. The control software in set-top boxes includes a real-time multi-tasking operating system with extensive multimedia support. Along with digital TV functionality, the control software provides an easy to use functional interface for set-top capabilities, such as MPEG decoding, high-speed broadband network interface, 2-way communications and graphics. An application-level software called the navigator performs basic TV functions and has the ability to download and execute interactive multimedia applications from network servers.

Variable bit-rate compression (VBR) is known to be more efficient than constant bit-rate (CBR) compression. However, since most transmission media convey a constant bit rate, most applications use CBR compression. In multi-program applications, such as satellite and cable television, a technique called joint bit-rate control can be used. With joint bit-rate control the bit rates of individual programs are allowed to vary, but the sum of all bit rates is kept constant. Since a joint control is involved, the encoders should be geographically close. Joint bit-rate control is different from a technique called statistical multiplexing, which is proposed in combination with ATM networks. In this paper, the benefits of joint bit-rate control are studied. This study involves both a theoretical analysis and a verification with experiments. In the experiments a software simulation was used that included the two basic system aspects of joint bit allocation and variable bit-rate buffer management. Both theory and practice indicate that joint bit-rate control gives a significant gain even for a small number of programs. For instance, extra programs can be transmitted over the same channel, e.g. a satellite link, if joint bit-rate control is used.

Philips Research has been very active in the field of digital video compression for several years. It has recently participated in the specification of the MPEG-2 Video Standard, and has designed a real time MPEG-2 video encoder now available as a Philips product.

Some basic concepts about electronic programme guides and what Philips is doing in the area are explained, followed by a more detailed explanation of some key components needed in such a system. By way of example, some aspects of the Philips system are highlighted, both on the receiver and the transmitter side. Special attention is given to the constraining character of the digital video broadcast environment; some challenging problems for the design of an electronic programme guide in such environments are explained, and solutions are sketched.

In multimedia applications information is presented in different forms, such as text, picture, audio and video. As the volume of data increases, it is difficult to archive, access and retrieve information. This paper discusses various issues related to retrieving information in different formats. An overview of both existing and evolving approaches will be presented. A general architecture of a multimedia retrieval system and our initial efforts towards building that system will also be given.

In this paper, we describe the transmission standard selected for transmission of digitally compressed television signals over the cable network in Europe. This standard specifies the error correction coding, modulation and framing structures to be used in the transmitted signal. We review the key features of this standard and describe the architecture of one particular receiver implementation that conforms to this standard.