Abstract: A deflection unit of a cathode ray tube is provided with a cooling fan. The fan includes means for reducing the disturbing effect of the electric field generated by the fan on the deflection of the electrons, or the fan is arranged in such a manner that the disturbing effect is small.

Abstract: The invention relates to a color display device comprising an in-line electron gun (5) for generating three electron beams (6,7,8), and a convergence unit (14′) to dynamically influence the convergence of the electron beams, preferably to decrease a distance (p) between the electron beams. The convergence unit (14′) comprises a ring-shaped element (21′) having four coils (22′). The coils (22′) comprise electrically conductive wires, which have been toroidally wound in a winding direction and according to a winding density distribution N (&phgr;) given by N (&phgr;)=N0 cos (2&phgr;). Here &phgr; is an angle enclosed by the X-direction and a line between an element of the coil and the center, which ranges between 0° and 360°, N0 is the winding density at &phgr; equal to 0°, and the sign of N &phgr; denotes the winding direction.

Abstract: The invention relates to a color display device comprising an in-line electron gun (5) for generating three electron beams (6,7,8), and a convergence unit (14) to dynamically influence the convergence of the electron beams, preferably to decrease a distance (p) between the electron beams. The convergence unit (14) comprises a ring-shaped element (21) having four coils (22) and a longitudinal axis (24). A cross-section of the ring-shaped element (21) with a plane perpendicular to the longitudinal axis (24) is a circle with the longitudinal axis as its center and the ring-shaped element (21) forming the circumference. Each coil extends over the circumference over an angle &phgr; having a value between 50° and 75°.

Abstract: A cathode ray tube having a deflection unit, the play between the deflection unit (11) and the envelope (4) being different for two perpendicular (x and y) directions. This enables the tilt of the deflection unit relative to the envelope to be greater in a direction than in a direction at right angles to said direction. By virtue thereof, the distance between the deflection unit and the electron beams can be reduced, so that the deflection requires less energy and can be improved.

Abstract: The device is provided with an optical fiber bundle (5) having a first linear end face (9) at the document side and a second end face (11) whose shape is adapted to the shape of the detection system (3).To reduce the quantity of disturbing light from the light source (43; 61, 62; 44), which may reach the detection system (3), to a maximum possible extent, and to increase the quantity of signal light from the document (1), the second end face (11) is provided with an optical system (13, 14; 50; 70) for an improved coupling in and for reflections. The first end face (9) may also be provided with an optical system (16, 17) for reducing unwanted reflections.

Abstract: Flat and slightly convex pyrolytic graphite grid electrodes are very suitable for use in electric discharge tubes, are example in ion sources, cathode-ray tubes, travelling waveguides and transmitter tubes. It has proved possible to manufacture such electrodes by manufacturing the grid and the grid holder of the pyrolytic graphite electrode from one piece of pyrolytic graphite. Such integral grid electrodes have very good mechanical and thermal properties.

Abstract: In a color display tube including an envelope, a display screen, an electron gun system for producing and focusing a plurality of electron beams directed at the display screen, and coils for deflecting the beams, convergence of the beams independently of focusing is effected by a helically wound resistive element disposed in the envelope between the electron gun system and the deflection coils. The element surrounds the electron beams and is dimensioned such that, when predetermined potentials are applied thereto, a potential gradient is produced along its length which establishes a relatively large diameter, strong convergence lens through which the beams pass.

Abstract: Display device includes a cathode ray tube having an envelope 1 with a number of reference surfaces on the walls of V-shaped grooves provided on positioning studs 14. The deflection unit 10 is provided with adjustable camming members 15 which lie against respective reference surfaces. The position of the deflection unit 10 relative to the envelope 1 can be adjusted by rotating camming members 15.