Abstract: A flat display device, preferably of the PALC type, in which the plasma channels are formed by etching in a substrate laterally-spaced channels and bonding a thin dielectric sheet over the etched substrate. Adjoining each of the channels are shallow ledges, also formed by etching, which serve as recessed areas to receive enlarged ends serving as contact pads for each of the electrodes. Holes are formed in the thin dielectric sheet and contact material deposited on the bonded thin dielectric sheet such that the deposited material makes electrical contact with the underlying electrode contact pads and seals off the holes, which allows a plasma-forming atmosphere to be provided in the channels. This arrangement results in a glass-to-glass interface between the substrate and the thin dielectric sheet, which allows anodic bonding to be employed to assemble the two elements and thus eliminates the frit glass sealing process required in other constructions.

Abstract: Magnetic head (51) having a contact face (59) for cooperation with a tape face (55a) of a magnetic tape (55). The magnetic head comprises a transducing structure having at least one transducing gap (57) terminating in the contact face. The contact face is provided with at least one cleaning groove for cleaning the tape face, which groove extends parallel to the transducing gap and has at least one wall portion (61a, 62a) oriented at least substantially transversely to the contact face and constituting a scraping edge (61b, 62b) at the contact face.

Abstract: An illumination system (3) comprises an optical waveguide (9) of an optically transparent material having an exit surface (19) and four end faces (13, 14, 15, 16). The light from a light source (11) is coupled into the optical waveguide (9) via at least one of the end faces (13). The illumination system, for an LCD, further has a reflective polarizer (21) in combination with a diffuser (23) for polarizing the light supplied by the light source (11). The reflective polarizer (21) is integrated with the optical waveguide and constitutes the surface (25) of the optical waveguide (9) which is located opposite the exit surface (19). The diffuser (23) is present on a surface of the polarizer (21) remote from the optical waveguide (9).

Abstract: A liquid crystal display cell having a compensation layer of (polymer) material deposited from the gaseous phase. To obtain a smaller angle dependence, the birefringence of the compensation layer is rendered complementary to that associated with a given voltage across the liquid crystal cell by giving the optical axis of the compensation layer an angle to the direction transverse to the cell.

Abstract: A TFT active matrix display device comprising an array of display elements (12), e.g. LC display elements, each connected to the drain of a TFT (17) whose gate and source are connected respectively to a row conductor (18) to which selection signals are applied by a scan drive circuit (21) and a column conductor (19) to which display data signals are applied by a data signal drive circuit (25) in the form of time dependent signals comprising pulse width modulated signals derived from an input digital video signal and representing video sample values. During the selection period the TFTs are biased to act as current sources such that their associated display elements (12) are charged to a level dependent on the duration of the applied signals. The digital to analogue conversion of the video signal is thus completed at the picture elements.

Abstract: By providing a semiconductor device such as a cold cathode (7) with extra zener or avalanche structures (26, 27 and 32, 33, respectively) a robust structure is obtained which is resistant to damage during manufacture and use of a vacuum tube. The semiconductor zones (26, 27, 32, 33) are thus also utilized for realizing electron optics (particle optics).

Abstract: The display device comprises a first and a second substrate (52, 53) between which a number of pixels arranged in rows and columns are situated, and said first substrate (52) being provided with a group of electrodes (56, 56', 56") and said second substrate (53) being provided with a group of electrodes (57, 57', 57") for driving the pixels. The display device is characterized in that electrodes of the group of electrodes (56, 56', 56") extend as far as an edge (a) of the first substrate (52), and that the edge (a) of the first substrate (52) and a corresponding edge (a') of a second substrate (53) are positioned relative to each other such that the corresponding edge (a') projects a distance d.sub.1 beyond the edge (b) of the first substrate (52).

Abstract: In a display device of the reset type, drive asymmetries in mutually offset picture electrodes (6) occur due to capacitive crosstalk differences between these picture electrodes (6) and column electrodes, and consequently lead to artifacts.These crosstalk differences are eliminated by choosing a layout for a picture electrode (6) and the surrounding electrodes (8, 18) and switching elements (9, 19), which layout, viewed in consecutive rows, is mirror-symmetrical.

Abstract: The invention relates to an illumination system comprising an optical waveguide of an optically transparent material having an exit surface and a plurality of end faces, and a light source whose light is coupled into the waveguide via at least one end face of the waveguide. The waveguide further comprises polarizing means for polarizing the light emitted by the light source. The waveguide comprises at least two layers, of which one layer comprises an optically anisotropic material having refractive indices n.sub.e and n.sub.o and the other layer comprises an optically isotropic material having a refractive index n.sub.i, in which one of the refractive indices n.sub.e or n.sub.o is equal to n.sub.i. For the refractive indices, n.sub.e or n.sub.o should be equal or substantially equal to n.sub.i in order that polarization separation occurs at the interface between the isotropic and the anisotropic material. The invention also relates to a flat-panel picture display device including such an illumination system.

Abstract: A circuit arrangement for the square-wave modulated high-frequency voltage operation of a discharge lamp, including means to control the duty cycle of the square wave, has a measuring circuit for detecting the ignition of the discharge lamp during each cycle of the substantially square-wave modulation and a timer circuit coupled to the measuring circuit for rendering the amplitude of the high-frequency voltage substantially equal to zero when a time interval has elapsed after the ignition of the discharge lamp, whereby the luminous flux of the discharge lamp fluctuates to a low degree only.

Abstract: A display system which comprises a means for changing the s/a.sub.v and/or p/a.sub.h ratio, the scanning-line pitch s and/or the pixel pitch p of incoming signals.

Abstract: An in-line electron gun includes main lens electrodes, a common aperture and, at a distance from the common aperture, three in-line apertures in a plate-shaped part. The outer apertures extend, viewed in a direction transverse to the plate-shaped part, beyond the common aperture.

Abstract: An additional switching element (18) is associated with a switching element (8) in a display device (1), which additional switching element is short-circuited by a picture electrode (5) or row electrode (7) when the switching elements function normally, so that there is no voltage drop across the second switching element (18) when a pixel (11) operates satisfactorily. Consequently, the redundant element does not have any capacitive influence on the operation of the pixel or the transmission/voltage characteristic of the pixel. If the switching element (8) is defective, the second switching element (18) can be switched on.

Abstract: A plasma-addressed liquid crystal color display device comprising a layer of liquid crystal material, data electrodes coupled to the liquid crystal layer and adapted to receive data voltages for activating pixels of the liquid crystal layer, and a plurality of ionizable-gas-filled plasma channels extending generally transverse to the data electrodes for selectively switching on said liquid crystal pixels. The plasma channels are sealed off by a thin dielectric sheet, and a color filter layer is provided in the device through which changes in the attenuation of the liquid crystal pixels may be viewed to obtain a color image. To reduce the magnitude of the data voltages needed to activate the device, the device layers are configured and given compositions such that a much higher fraction of the applied data voltages appears across the liquid crystal layer thereby allowing a smaller data voltage to be used to obtain the same effect on the liquid crystal pixels.

Abstract: A magnetic tape apparatus intended for consumer use includes at least one digital head with nine digital transmission gaps for reading and/or writing compressed digital information in longitudinal tracks on a magnetic tape. The apparatus also includes electronic circuitry for compressing the digital information prior to writing, and for expanding the digital information after reading. This arrangement enables at least playback of digital audio information at the same frequency used for analog compact cassettes, so that inclusion of an analog head enables playback of analog compact cassettes as well.

Abstract: A process and apparatus are described for custom magnetizing a magnetic ferrite ring on the outside of the neck of a color cathode ray tube (CRT), in order to provide correction of convergence, color purity and frame errors in the CRT. The two step process provides for a first coarse correction step and a second fine correction step, each step involving bringing the ring to an initial state of magnetic saturation, and then custom magnetizing the ring using a series of high power AC pulses and low power DC offsetting fields, via cylindrical coils positioned around the periphery and in close proximity to the ring.

Abstract: By selecting the number of apertures per vertical row in the shadow mask of a color cathode ray tube to be in the range between 615 and 650, such a cathode ray tube can be used both in a PAL, an NTSC system and a MUSE system without the occurrence of disturbing Moire effects. In a second embodiment the number of apertures per row ranges between 425 and 450.

Abstract: A method of metallizing an electrically insulating plate, for example, of glass having a large number of holes. Said relatively small holes are internally provided with a metal layer and the plate is provided with metal tracks. The metal used is mainly aluminum. The aluminum is coated with a thin protective layer of chromium, cobalt, nickel, zirconium or titanium. Said protective layer makes it possible to use a photosensitive, cataphoretic lacquer to mask the metal layer in patterning and etching thereof. The method can very suitably be used for the manufacture of selection plates for thin electron displays.

Abstract: The Application relates to an illumination system comprising a fluorescent lamp and a broadband, cholesteric polarizer. Such a polarizer contains a layer of a polymeric material having a cholesteric order, which material is ordered in such a way that the axis of the molecular helix extends at right angles to the layer. The broadband character of the polarizer is obtained by causing the pitch of the molecular helix to increase from a minimum value at a first surface of the cholesteric layer to a maximum value at the second surface of the layer. In accordance with the invention, the polarizer should be positioned in the illumination system in such a manner that the cholesteric layer is directed towards the fluorescent lamp with its first surface. In addition, the value of the product p.sub.max.n.sub.e of the maximum value of the pitch in the cholesteric layer p.sub.max and of the extraordinary refractive index n.sub.e must range between 0.61 micron and 0.76 micron.

Abstract: A light emitting device for use in lighting and/or display applications includes a UV/blue LED located in a depression having reflecting sidewalls, a light transmitting material surrounding the LED and filling the depression, and a phosphor in the form of particles either dispersed in the light transmitting material or adhered to the surface of the LED. The sidewalls reflect UV as well as visible light, thus enhancing the efficiency of the device. Optical filters located on the top of the LED and/or the bottom of a UV absorbing glass plate covering the depression further enhance efficiency and/or spectral characteristics of the emitted light.