Abstract: A protective sleeve of quartz surrounding a metal halide arc tube is fixed to upright portions of a frame by means of retaining rings. The frame has lower ends formed with coils fitted over the glass stem in an interference fit, thereby insulating the frame from the electrical leads sealed in the stem. An intermediate portion of the frame fits closely in the opposite end of the lamp to stabilize the burner assembly and shield.

Abstract: A rear projection screen (1) comprising a lenticular structure (5) and a Fresnel structure (4). The Fresnel structure (4) has riser edges (9) and Fresnel facets (7). The Fresnel facets (7) are divided into two parts. The first part (11) encloses an angle .psi. with the plane of the projection screen. The second part (13) is substantially parallel to the plane of the screen. The Fresnel structure (4) and the lenticular structure (5) are fixed to each other at the second parts of the Fresnel structure.

Abstract: A rear projection screen which includes a front lenticular surface, a diffusion region behind the lenticular surface, a non-diffusion region behind the diffusion region, and a rear phase grating surface, when used with high magnification projection systems, exhibits reduced speckle when compared to other rear projection screen without such a grating.

Abstract: Support device (53) provided with a first part (69) and a second part (71) which is supported relative to the first part by means of a gas spring (73) having a pressure chamber (75). A gas supply (117), which compensates for gas leakage from the pressure chamber (75) during operation, is connected to an intermediate space (119) which is in communication with the pressure chamber (75) via a pneumatic restriction (121). The gas pressure present in the intermediate space (119) is held as constant as possible during operation by means of a control loop (123), to prevent transmission of pressure fluctuations which are present in the gas supply (117) to the pressure chamber (75) as much as possible. Such pressure fluctuations are undesirable in the pressure chamber because they cause mechanical vibrations in the second part of the support device and the device to be supported.

Abstract: Color rendering indices Ra,8 between 80 and 90 and R9 greater than 20, and a color point on or near the Planckian curve, are achieved with a lamp vessel provided with a luminescent screen including a first luminescent substance which emits predominantly between 520 nm and 565 nm, a second luminescent substance which emits predominantly between 590 nm and 630 nm, and a third luminescent substance which emits predominantly in the range between 615 nm and 780 nm.

Abstract: Apparatus for mixing light from discrete LED light sources utilizes beam splitters which each have a semi-reflective layer which partially transmits and partially reflects light of any wavelength incident thereon. Each semi-reflective layer is situated in a transparent prismatic black between reflective surfaces on parallel outside faces of the block so that two parallel input beams are mixed and transmitted as two parallel mixed beams of like color. For a square array of light sources, a first mixing stage consists of two such prismatic blocks arranged side-by-side, and a second mixing stage consists of two such prismatic blocks arranged side-by-side and rotated 90 degrees to the first stage. The second stage is arranged to receive a square array of mixed beams and produces four identical output beams. The colors of the light sources are chosen so that all output beams are white.

Abstract: The electric incandescent lamp has a sintered glass plate through which current conductors and a metal tube extend. An incandescent body is connected to the current conductors aligned with respect to the plate. A glass bulb is present over the incandescent body, secured to the plate in a gastight manner by means of enamel. A water getter and a heavy gas at an elevated pressure are present inside the glass bulb.

Abstract: At least one of the electrodes (6a) has a coil (60a) of a refractory metal which is electrically connected to current supply conductors (7a, 7a') which extend to outside the discharge vessel. The coil (60a) has a central portion (61a) which is coated with an electron-emitting material and an end portion (62a, 62a) on either side thereof, which end portions are covered with a protecting material which is mainly formed by one or more oxides of calcium and/or magnesium.

Abstract: A power cord transformer includes a core of ferromagnetic material, a primary coil and a secondary coil both provided around the core. The core and coils have such a shape that the distance between two points on the primary coil and also the distance between two points on the secondary coil is always smaller than twice the largest axis of the power cord cross-section.

Abstract: A light-transmissive discharge vessel (1) encloses a discharge space (10) which contains an ionizable filling comprising an evaporable component. The low-pressure discharge lamp is also provided with coil for maintaining an electric discharge in the discharge space, and with a carrier (3) with a resilient body (30) and an open holder (31). The resilient body (30) is clamped inside a tube (14) which communicates with the discharge space (10). The holder (31) is clamped inside the resilient body (30). In the absence of the holder (31), the resilient body (30) can be inserted in a released state in the tube (14) with play (x).

Abstract: A discharge vessel with a ceramic wall encloses a discharge space in which besides a rare gas also an ionizable filling comprising at least NaI is present. Two electrodes having tips with a mutual distance EA are arranged in the discharge space which discharge vessel has an internal diameter Di over at least the electrode distance EA. The discharge space is Hg-free and the ionizable filling further comprises Zn and the electrode distance EA and the internal diameter Di comply with the relation 1.ltoreq.EA/Di.ltoreq.4.

Abstract: Discharge lamp utilizes a current carrying frame member which supports an arc tube and positions it centrally in a glass envelope having a closed end with an inside surface. The frame member has a first end fixed to a lead in the stem and a second end formed with first and second cantilevers connected by a 180 degree bend to resiliently position the frame member in the closed end of the envelope. A metal halide discharge lamp having an elliptical glass envelope and a cylindrical end utilizes a frame wherein the cantilevers are displaced apart to load a hooked end formed on the second cantilever against the inside surface.

Abstract: A luminescent material of general formulaLn.sub.y/3 Na.sub.x-y (Al.sub.x Si.sub.192-x O.sub.384)(MO.sub.3).sub.zwherein 0<x<96, 0<y<96, y<x and z<20, and Ln comprises one or more elements chosen from the group formed by Sc, Y, La and the Lanthanides and wherein M comprises one or more elements chosen from the group formed by Mo, W, V, Nb and Ta. Luminescent materials of this general formula are relatively cheap and are very suitable for use in low pressure mercury discharge lamps of the three band type.

Abstract: A lampholder in accordance with the invention can suitably be used for a low-pressure discharge lamp (a) which operates at a high frequency and which comprises an elongated, tubular discharge vessel (b), said lamp being provided with a pair of electrodes (c, c') for maintaining an electric discharge in the discharge vessel. The lampholder (0) has contacts (1, 1') for connecting a high-frequency power supply (4), said contacts being electrically connected to a first (2) and a second terminal (2') for connecting the lamp. The second terminal is further removed from the contacts than the first terminal. A compensation conductor (6) extending between the first (2) and the second terminal (2') is connected to said first terminal (2). This leads to a reduction of conducted interference.

Abstract: A white light emitting luminaire includes a plurality of LEDs in each of the colors red, green, and blue with a separate power supply for each color and a photodiode arranged to measure the light output of all the LEDs. The light output of each color is measured by an electronic control circuit which turns off the LEDs for the colors not being measured in a sequence of time pulses. The measured light output for each color is compared to a desired output, which may be determined by user inputs, and corrections to the current for each color are made accordingly.

Abstract: The invention relates to a driving device for at least two rotation elements, which device comprises at least one piezoelectric driving element. The object of the invention is to provide such a driving device having a high efficiency and allowing a more flexible positioning of the rotation elements.The invention is characterized in that the piezoelectric driving element comprises a piezoelectric resonator and at least two friction elements arranged on the piezoelectric resonator and disposed opposite one another, the piezoelectric resonator with the friction elements is arranged between the two rotation elements and is restrained by means of a pre-loading force, each one of the friction elements acts upon one of the rotation elements, and electrical means for the excitation of a vibration mode of the piezoelectric resonator have been provided.

Abstract: Anodized aluminum anode and cathode foils are interleaved in a stack separated by spacers saturated with electrolyte in an enclosure. The anode foils and cathode foils have tabs which protrude from the housing and are cold welded to leads outside the housing, where they are not exposed to electrolyte. This permits using copper leads, which can be soldered to traces on a printed circuit board. A flat capacitor can be fixed underneath a PCB or even used as the substrate for a circuit, resulting in high volume efficiencies and the possibility of using it as a heat sink for other components.

Abstract: A road marking unit (1) according to the invention comprises a house (10) with a light transmissive window (20). In the house (10) is arranged an electro-optic switch (30). In an activated state of the road marking unit (1) the electro-optic switch (30) achieves that light is reflected from the window (20) back to the window (20). In a de-activated state of the road marking unit (1) the electro-optic switch (30) achieves that light from the window (20) is absorbed. The road marking unit (1) of the invention has the advantage that it can also in bright environmental light it can be switched between visible and invisible.

Abstract: An illumination unit comprises a high-frequency supply (1) and a low-pressure discharge lamp (2). The high-frequency supply (1) is provided with a first and a second output (13a, 13b). The outputs each deliver a HF-varying voltage with respect to ground. The voltages have the same magnitude and are in phase opposition. The supply (1) is provided with a further output (13c) which is substantially free of high-frequency voltage variations with respect to ground. The low-pressure discharge lamp (2) is provided with a tubular discharge vessel (20) with an ionizable filling.

Abstract: A bipolar transistor (3) is provided with a first main surface (4) in contact with a conductive mounting surface (2), and with an opposed second main surface (12) having connection pads (5, 6, 40) for an emitter, base, and collector. The lateral dimensions of the conductive mounting surface (2) are practically equal to the dimensions of the first main surface (4) of the transistor (3), and may thus be relatively small. The high-frequency properties of the transistor (3) are strongly determined by the size of the conductive mounting surface (2), which through an insulating substrate (1) forms a parasitic capacitance with a conductive ground surface (18), which capacitance is connected to the transistor (3). This parasitic capacitance is very important especially for high-frequency applications. Furthermore, the bonding wires (E, B) for the connection pads of emitter and base are shorter than in the prior art because they need not pass over a relatively large conductive mounting surface (2).