Abstract: Texture mapping or video mapping is performed in such a way as to obtain perspectively correct images, while at the same time not requiring excessive computational overheads. Non-linear functions required to achieve perspectively correct images are stored in the form of look-up tables. Depth extents at the extremes of a locus of interpolation are compared and from this comparison a particular look-up table, or a pair of look-up tables, are selected. When a pair of look-up tables are selected, it is possible to linearly interpolate between the two, in order to obtain a closer approximation to the desired non-linear response.

Abstract: An illumination unit including an electrodeless low-pressure discharge lamp (20) and a supply device (50). The lamp has a discharge vessel (30) which encloses in a gastight manner a discharge space (31) which is provided with an ionizable filling. The lamp (20) further has a coil (40) provided with a winding (42) around a sintered core (41) of polycrystalline ferrite material, which winding (42) is connected to the supply device (50). The coil (40) is capable of inducing a high-frequency magnetic field which maintains a discharge in the discharge space (31). The losses in the core (41), when measured at room temperature in a magnetic field with a frequency of 3 MHz and a magnetic flux density of 10 mT, amount to at most 150 mW/cm.sup.3. This has the advantage that the lamp (20) ignites comparatively quickly and loads the supply device (50) comparatively weakly during ignition. The supply device (50) as a result can have a comparatively long useful life.

Abstract: A dimming ballast for use with a phase control dimmer, and particularly a triac dimmer, includes an EMI filter selected with a high impedance to avoid excessive voltage and peak currents in the filter due to resonance with the phase controlled AC waveform at low conduction angles, when the load presented by the lamp is low. The EMI filter includes a filter capacitor connected at the output of a rectifier. The ballast also includes circuitry to sense the rectified DC voltage and to discharge the filter capacitor when the rectified voltage is at or near zero, to thereby keep the EMI filter loaded and prevent misfiring of the triac dimmer. In a favorable embodiment, the sensing and discharge function is carried out by a pre-conditioner of the switched-mode type.

Abstract: A low-pressure mercury discharge lamp with a very good color rendering and with a color point (x.sub.L, y.sub.I) on or close to the Planckian locus, includes a gastight, radiation-transmitting envelope which contains mercury and rare gas, and a luminescent layer includinga first luminescent material activated by bivalent europium and having an emission band whose maximum lies between 470 nm and 500 nm and whose half-value width is at most 90 nm,a second luminescent material activated by bivalent manganese and having at least an emission band mainly in the red region of the visible spectrum,a third luminescent material with a band emission whose maximum lies between 430 nm and 490 nm,a fourth luminescent material with emission mainly between 520 nm and 565 nm, anda fifth luminescent material with emission mainly between 590 nm and 630 nm.

Abstract: A high pressure discharge lamp having a discharge vessel with opposing end chambers includes discharge electrodes each consisting of an open elongate filament of refractory metal wire having a plurality of succesive coil turns extending transverse to the longitudinal axis of the discharge vessel. The filament electrodes are dimensioned so that the discharge arc which terminates thereon is sufficiently retracted into the end chamber of the discharge vessel so that the fill constituents condense on a region of the discharge vessel which is primarily axially between the filament electrodes. In a favorable embodiment, the lamp is a metal halide lamp in which the electrode and the discharge sustaining fill is free of thoria and its compounds.

Abstract: A magnetic tape apparatus includes a forward drive wheel which is coaxial with a forward winding mandrel, a reverse drive wheel which is coaxial with a reverse winding mandrel, and a drive device for driving the forward drive wheel and the reverse drive wheel. The drive device has a drive shaft which can be set to different operating positions. The drive shaft includes a friction-wheel drive portion for driving a friction-wheel portion of the forward drive wheel, and a toothed-wheel drive portion for driving a toothed-wheel portion of the reverse drive wheel. In addition, the drive device can drive the forward drive wheel via a toothed-wheel portion thereof, for which purpose the drive device has a toothed-wheel drive which can be set to a fast-forward driving position in which it is in mesh both with a toothed-wheel drive portion of the drive shaft and with the toothed-wheel portion of the forward drive wheel.

Abstract: The invention relates to a magnetic tape cassette device in which a cassette (2) containing the magnetic tape can be introduced into a cassette tray and can rest, loosely held, in the cassette tray (1) before or after the moving of an operating lever (13) which can move with the cassette housing during introduction, the operating lever (13) interacting with a tappet (29), which in the introduction position of the cassette pushes against the latter in order that it may be hindered from free movements in the cassette tray (1). The tappet lever (23) is designed as a double-armed swivel part (23), the tappet (29) being provided at a free end (28) of a first swivel arm (24) of the swivel part (23) and the connection to the operating lever (13) being provided at the end of a second swivel arm (25) of this swivel part (23).

Abstract: The invention relates to an X-ray tube having a rotary anode which is rotatably supported in a vacuum-tight housing by at least one metal-lubricated sliding bearing of which at least the cooperating bearing surfaces consist of a W-alloy and in which the lubricant is Ga or a Ga-alloy.In order to extend the life of the X-ray tube, in particular at operating temperatures of the bearing above 400.degree. C., a mechanically readily machinable W-alloy is used which comprises from 2 to 27% by weight of Re.

Abstract: Luminaire provided with a bowl-shaped reflector for an elongated light-emitting part of a light source to be arranged substantially on the principal axis of said reflector. The reflector has a reflecting surface composed of elongated facets whose longitudinal sides extend from adjacent the center to the peripheral edge of the reflector. The facets are concavely curved in a cross-section comprising the principal axis and are straight in a plane at right angles to the peripheral axis and constitute a regular polygon, the axis of symmetry of a facet extending in accordance with a curve approaching the shape of a parabola.

Abstract: Low-pressure mercury vapor discharge lamp having a discharge vessel which is sealed in a gastight manner and is formed in such a way that the ends at which the electrodes are located are adjacent. The ends are secured to a lamp cap having a shell accommodating a starter and possibly a capacitor. The shell has guide walls for guiding an inner pair of electrode leads past the starter. The electrode leads, starter leads and capacitor leads terminate near the open end of the shell for ease of connection. The open end is closed by a cover with a snap connection. Current connection pins are adjacent the shell and are aligned with an outer pair of electrode leads for ease of assembly.