Abstract: The present invention relates to a display device comprising a cathode ray index tube (1) having a neck portion (1?) and a screen portion (1). The display device comprises an electron gun assembly (3) for generating a plurality of electron beams (3R,3G,3B), positioned in the neck portion (1?) of the cathode ray index tube (1), a deflection unit (5), placed around the neck portion (1?) of the cathode ray index tube (1), for deflecting said plurality of electron beams (3R,3G,3B), and a convergence unit (6) for converging said plurality of electron beams (3R,3G,3B). The deflection unit (5) is placed at an axial distance from said electron gun assembly (3), closer to said screen portion (1?). The convergence unit (6) is placed in close proximity to the deflection unit (5).

Abstract: The invention relates to a deflection unit for cathode ray tubes in which the energy for deflection is reduced. This is done by providing a magnetic material between frame coils and line coils of the deflection unit. In an advantageous embodiment of the invention, first void spaces as well as second void spaces between the frame coils and a yoke ring and/or third void spaces between wire strands of the frame coils are filled. A deflection energy reduction of up to 30% can be obtained.

Abstract: A dynamic focusing circuit includes a transformer with a primary winding for receiving a line-frequency deflection current and a secondary winding for supplying a transformed deflection current. An integrator, coupled to the secondary winding, generates a line-frequency focusing voltage from the transformed deflection current. A waveform generator coupled to the secondary winding generates an additional line-frequency focusing voltage and superimposes the additional line-frequency focusing voltage on the line-frequency focusing voltage.

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 and deflecting means (51) for deflecting the electron beams (6, 7, 8). The convergence unit (14′) comprises a ring-shaped element (21′), said ring-shaped element comprising two parts, a first part (60) being positioned closer to the in-line gun (5) than a second part (68), and the first and/or the second part having four coils (22′) for generating a magnetic quadrupole field.

Abstract: A color display device having 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′) includes a ring-shaped element (21′) having coils (22′) formed by 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;)+C where &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 a given winding density, the sign of N (&phgr;) denotes the winding direction, and C is a constant different from zero, and preferably equal to −N0.

Abstract: The invention relates to a dynamic focusing circuit (100) for generating a line-frequency dynamic focusing voltage (Vl1) which can be used to control a DAF section (220) of a cathode ray tube (CRT). The dynamic focusing circuit (100) receives a line deflection current (Id1) and transforms and integrates said current so as to obtain the line-frequency focusing voltage (Vl1). The dynamic focusing circuit also generates a further line-frequency focusing voltage (Vl2) and adds this voltage to the line-frequency focusing voltage (Vl1). By applying the invention, the line-frequency focusing voltage (Vl1) is suitable for dynamically focusing the electron beam (201) in a cathode ray tube (CRT) with a relatively large deflection angle of, for example, 120°. It has both a sufficient amplitude and a suitable shape, for example, a bathtub shape.

Abstract: A color display device comprises an electron gun, a display screen and a color selection electrode as well as a deflection means. The distance between the electron beams is dynamically varied, i.e. the distance between the electron beams in the deflection plane decreases as the beams are deflected in at least one direction. The decrease of the distance enables the distance between the color selection electrode and the display screen to be increased in that direction. As a result, the curvature of the color selection electrode is increased, which has a position effect on the strength, doming and microphonics of the color selection electrode. The distance is dynamically varied by first and second means, the first means being arranged in or near the pre-focusing parts of the electron gun. Said first means comprise magnetic means outside the neck of the CRT for generating dynamically varying magnetic fields, and magnetic field conducting means to conduct the fields to a position near the electron beams.

Abstract: The present invention relates to a display device comprising a cathode ray index tube (1) having a neck portion (1″) and a screen portion (1). The display device comprises an electron gun assembly (3) for generating a plurality of electron beams (3R,3G,3B), positioned in the neck portion (1″) of the cathode ray index tube (1), a deflection unit (5), placed around the neck portion (1″) of the cathode ray index tube (1), for deflecting said plurality of electron beams (3R,3G,3B), and a convergence unit (6) for converging said plurality of electron beams (3R,3G,3B). The deflection unit (5) is placed at an axial distance from said electron gun assembly (3), closer to said screen portion (1′). The convergence unit (6) is placed in close proximity to the deflection unit (5).

Abstract: A color cathode ray tube has quadrupole elements which increase and decrease the distance between the electron beams as a function of the deflection. Two co-operating elements have their windings connected in series with each other to minimize dissipation in the driving circuits. One driving circuit provides a common current which flows through both quadrupole elements, while another driving circuit provides a difference current to a node between the quadrupole elements.

Abstract: A color display device comprises an electron gun, a display screen and a color selection electrode as well as a deflection means. The distance between the electron beams is dynamically varied, i.e. the distance between the electron beams in the deflection plane decreases as the beams are deflected in at least one direction. The decrease of the distance enables the distance between the color selection electrode and the display screen to be increased in that direction. As a result, the curvature of the color selection electrode is increased, which has a positive effect on the strength, doming and microphonics of the color selection electrode. The distance is dynamically varied by first and second means, the first means being arranged in or near the pre-focusing parts of the electron gun. Said first means comprise magnetic means outside the neck of the CRT for generating dynamically varying magnetic fields, and magnetic field conducting means to conduct the fields to a position near the electron beams.

Abstract: The color display tube (1) has a display window (3) and a curved shadow mask (13). The inner surface (15) of the display window (3) may be substantially flat or it may be curved with a curvature smaller than the curvature of the shadow mask (13). The distance Qp from the shadow mask (13) to the screen (6) at the inner surface (15) of the display window (3) of the color display tube (1) according to the invention is larger by a positive integer, not being a multiple of three, for all positions p on the screen (6) than this distance Q0p in prior art tubes.