Philips Journal of Research最新文献

In order to use pre-operative images during an intervention for navigation, they must be registered to the patient's co-ordinate system in the operating theatre or to an intra-operative image. For the registration to be valid in the case of patient movements, the registration must be updated or the patient movement must be tracked. One problem in this area is the registration of intra-operatively acquired X-ray fluoroscopies with 3D CT images obtained before the intervention as well as motion tracking for this setup. The result can be used to support the placement of pedicle screws in spine surgery or aortic endoprostheses in transfemoral endovascular aneurysm management (TEAM). The different approaches to 2D/3D registration are discussed and a novel voxel-based method is presented: using a small part of the CT image covering only the vertebra of interest, pseudo-projections are computed and the resulting vertebra template is compared to the X-ray projection using a new similarity measure which is called pattern intensity. Application, performance and registration accuracy are discussed and demonstrated by application to images of a TEAM procedure and of a spine phantom.

The luminescence efficiency of polymer light-emitting diodes is determined by the efficiency of radiative recombination of excitons. In a joint research programme, Leiden University and Philips Research are conducting a theoretical investigation on the dynamics of excitons in conjugated polymers. This article reviews part of the results obtained so far, describing the following phenomena: spectral diffusion, electric field-induced quenching, photobleaching and defect quenching.

The technology as used for passive integration is discussed. The build-up of passive components (integrated resistors, capacitors, and inductors, including interconnect) and the (eventually) following mounting and assembly technologies are described. The adaptations of the basic technology are described using a number of demonstrator examples from different application fields. Depending on these application areas, different constraints are valid. This is often related to the working frequencies of the devices and the modules, or the extra assembly of active components. Some results on the material characteristics are discussed, but the emphasis is on the description of technology.

An outlook is given on how the efficiency of future generation yoke-type magneto-resistive read heads may be improved through the use of oxidic layers. The effect of ferrite separation oxides, ferrite fluxguides and superconducting gap-oxides is discussed.

In this paper, we report on the lifetime of polymer LEDs fabricated at Philips Research. For single-layer LEDS, we find that the operational lifetime in nitrogen gas is limited by the stability of the indium-tin-oxide (ITO) anode. By using a polymeric capping layer for the ITO, we obtain more stable devices. In air, the lifetime is limited by black spot formation. Small pinholes in the cathode layer are the origins of the black spots. Water or oxygen may diffuse through these pinholes and react with the cathode, causing degradation. By encapsulating the devices we can prevent black spot formation. Our present 8 cm² devices have lifetimes of many thousands of hours at daylight visibility under ambient conditions.

Easy processing and mechanical flexibility make polymer light-emitting diodes (PLEDs) suitable candidates for large-area display applications. The understanding of the device properties of PLEDs is a key ingredient for further optimization. This article reviews a device model developed at Philips Research that describes the current and light generation of PLEDs as a function of applied voltage. The model is based on experiments carried out on poly(dialkoxy-p-phenylene vinylene) devices. The combination of the experimental results and model calculations have revealed that (1) the hole current is dominated by space-charge effects and a field-dependent mobility, (2) the electron current is strongly reduced by traps, and (3) the recombination process between the injected electrons and holes is of the Langevin-type. These results explain specific device properties of PLEDs such as a bias-dependent and temperature-independent electroluminescence efficiency (photon/carrier) and indicate directions for further improvement of the device performance.

In this paper tools to handle the magnetostatic aspects of thin-film tape head design are reviewed. Some illustrative results from transmission-line calculations on inductive write heads and yoke-type magnetoresistive read heads are shown. New is the application to nonlinear saturation effects in write heads. The design of an emboss head for writing servo tracks on tape is described. Finally, a new type of read head is discussed that utilizes anisotropy of the permeability instead of structuring of the fluxguides for obtaining very small track widths.

Miniaturisation and integration of passive components play an important role in today's components market. It can be achieved by applying thin-film technologies for capacitors, resistors and inductors; high component densities have been realised with ‘Passive Only Networks’. The dielectric materials used for integrated thin-film capacitors ranging from Si₃N₄, Ta₂O₅, TiO₂ to earth alkaline as well as lead perovskite layers are reviewed. The capacitor performances including temperature stability, insulation resistance, breakdown fields and endurance are discussed as a function of material composition.