U.S. Philips Corporation

U.S. Phillips Corporation

Piet G Barten

Jan Gerritsen

Jan Bijma

Joris A Nieuwendijk

Willem M Van Alphen

Otto Mensies

Johannes J Bos

Adrianus Hubertus Kantelberg

Johannes Van Den Boogert

Kees Tendeloo

Color display tube comprising an in-line electron gun, a self-convergent deflection coil, a shadow mask having a pattern of apertures and a display screen having a pattern of phosphor dots. The aperture pattern consists of apertures arranged in vertical rows with a substantially equal vertical aperture spacing between the centers of each pair of consecutive apertures in each row. The vertical rows of apertures are alternately staggered through half the vertical aperture spacing. The electron gun generates three electron beams in the vertical plane through the axis of the color display tube. The phosphor dots are arranged in vertical triplets. Both the apertures and the phosphor dots are horizontally elongated. The horizontal spacing between the vertical rows of apertures is preferably smaller than 1/2*.sqroot.3 times the vertical aperture spacing. A better definition due to a reduced deflection defocusing is achieved with this color display tube, without Moire phenomena occurring.

Color display tube having a reduced deflection defocusing

A color display tube having an in-line electron gun 5 and a deflection system 13. The deflection system 13 generates deflection fields having an astigmatic character, such that in a state-of-the-art electron gun overconvergence of the electron beams occurs on the display window. In a color display tube according to the invention, the electron gun 5 is changed such that this overconvergence is compensated by an underconvergence generated in the electron gun. The horizontal spot enlargement factor is reduced by the less astigmatic character of the deflection fields.

Color display tube, deflection system and electron gun

In a color display tube of the so-called 'in-line' type, the magnetic field which extends substantially parallel to the plane through the beam axes is distorted so as to be locally pincushion-shaped by means of field shapers at the end of the electron gun system. This effects coma correction for the rasters produced by the three electron beams at the display screen, without causing substantial deflection defocusing of the side beams.

Color display tube with magnetic field shaping plates

A beam index display tube which has a screen structure enabling a circular spot to be used and has vertical beam indexing. The screen (18) comprises a plurality of transversely extending, substantially contiguous lines (36 to 46), each line being composed of a plurality of triplets of different color emitting elements (R, G, B) and index elements (20) distributed along each line in accordance with a predetermined pattern. The phosphor elements in each triplet are spatially separated from each other, the intervening spaces being left empty, being occupied by an index element or being filled with a black matrix material. Additionally by staggering the triplets between adjacent lines then considered in a direction transverse to that of the spot scanning, no phosphor element is adjacent another phosphor element. Vertical indexing is made possible by the index elements (20) being offset heightwise relative to the direction of scanning. Alternate elements (20) are offset in alternate directions so that it is possible to determine if the scanning electron beam is too high or too low because additional indexing signals are generated.

Beam index display tube and display system including the beam index

A method of post deflection correction of electron beam misconvergence in a color display tube, the method comprising: providing at least one permanently magnetizable substantially annular element externally of the tube envelope on the screen side of the plane of deflection of the deflection yoke; measuring the convergence errors at the screen; and magnetizing the element as a multipole to correct for the measured errors. The annular element may be mounted directly on the tube envelope, or may be secured to the deflection yoke.

Method of correcting electron beam misconvergence in a color display

A color display tube in which the bridges between the apertures of the color selection electrode are situated substantially on substantially straight lines in the plane of the color selection electrode, which lines enclose an angle between 3.degree. and 8.degree. with the horizontal direction of deflection, effectively suppressing the occurrence of moire-patterns.

Color display tube with line screen having reduced moire

In a color display tube having an electron gun of the 'in-line' type for generating three electron beams situated with their axes in one plane, the electron gun includes curved field shapers at the end from which the beams exit into frame and line deflection fields. Each field shaper includes two or more plates of ferromagnetic material aligned along a curve and spaced from each other by slots. The plates are arranged symmetrically with respect to the plane and the central beam axis, and a concave side of each field shaper faces the three beam axes. At least the ends of each field shaper which are most remote from the plane have substantially flat plates extending in the direction of the central electron beam axis. By using such field shapers the losses in the line deflection field are small and substantially undistorted, while a desirable pincushion-shaped distortion of the frame deflection field is intensified.

Color display tube with magnetic field shaping means

A picture display panel is provided having an envelope with internal reinforcement partitions formed onto a display window. The display window is provided with substantially V-shaped grooves on the outside opposite to contact surfaces with the reinforcement partitions. The reinforcement partitions thus become substantially invisible from the outside. The outermost edges of these V-shaped grooves are preferably rounded, and the picture display window surface between juxtaposed grooves may be convexly curved into cylindrical lenses to make the reinforcement partitions even more invisible.

Picture display panel

A focusing electron lens having a controllable astigmatism. An auxiliary electrode affects the non-rotationally symmetrical field defined by two tubular electrodes to vary the convergence in one main direction while maintaining it constant in the other main direction. In an in-line electron gun system in a color television display tube, such a lens corrects for the effect of parastigmatic, self-converging deflection coil systems on the focusing of the electron beams.

Astigmatic electron lens for a cathode-ray tube

A picture display device in which velocity modulation of the electron beam is effected with a deflection correction signal derived from the video signal to be displayed. The brightness distribution influenced by this deflection correction signal in a sudden brightness transient is corrected by adding to the video signal a brightness correction signal which is predominantly proportional to the product of the video signal and a first derivative with respect to time of the deflection correction signal.

Picture display device

Because the deflection fields in color television display tubes on the display screen side often have a pin-cushion-shaped and barrel-shaped field distribution, a defocusing of the electron beams occurs upon deflection. By forming the barrel-shaped deflection field on the display screen side of the display tube so as to be pin-cushion-shaped on the neck side near each electron beam and simultaneously deforming the deflection field which is pin-cushion-shaped on the display screen side of the display tube so as to be barrel-shaped on the neck side near each electron beam, the effects of said defocusing of the electron beams as a result of the deflection are considerably reduced. The haze occurring in the vertical direction is also reduced.

Display tube for displaying color pictures

A ring is provided to correct the convergence, color purity and frame errors of a color display tube which ring is magnetized as a multipole and which is secured in or around the tube neck and around the paths of the electron beams. The magnetization of such a ring can best be carried out by energizing a magnetization unit with a combination of direct currents thereby generating a multipole magnetic field and then effecting the magnetization by generating a decaying alternating magnetic field which preferably varies its direction continuously.

Method of manufacturing a color display tube and color display tube

The method according to the invention consists in the determination of data of the convergence errors of a color display tube, data being derived from the said determinations for determining the polarity and the intensity of magnetic poles of a structure. The structure thus obtained generates a static, permanent, multipole magnetic field adapted to the convergence errors occurring, so that the errors are connected.

Method of manufacturing a static convergence unit, and a color display

Color television display tube of the shadow mask type with phosphor lines. In connection with the unequal center distances between the central electron spot and the two outermost electron spots of a triplet as a result of the properties of the deflection coils, the width of the phosphor lines is chosen to be so that the electron spots in the case of mislanding simultaneously cross the edge of the phosphor lines. As a result of this the 'white-remains-white' effect is obtained. The intermediate spaces between the phosphor lines of a triplet are preferably equal, which facilitates the inspection of the screens during the manufacture.

Color television display tube

An in-line CRT features a static convergence means. It has at most two permanent magnets in or around the tube neck before the deflection coils.

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Eindhoven, Netherlands

Piet G Barten