DE1163985B - Magnetic electron lens to reduce the line structure in television receivers - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Kl .: HOIj German class: 21g-13/22

Number: 1163 985

File number: T 20634 VIII c / 21 g

Filing date: August 23, 1961

Opening day: February 27, 1964

The invention relates to a magnetic electron lens for cathode ray tubes in television receivers, in the case of the two magnet systems arranged diametrically next to the tube neck of the Light spot displayed on the screen to reduce or eliminate the line structure to one Luminous line is stretched perpendicular to the line direction.

It is known the cross section of the cathode ray of a cathode ray tube of a television receiver by distorting the focussing field to stretch it into a luminous line, its The longitudinal direction extends perpendicular to the lines of the image grid. In such a known arrangement (U.S. Pat. No. 2,790,920) have one or more annular rings on the neck of the tube Permanent magnets magnetized in the direction of the electron beam and on its periphery ferromagnetic, originally non-magnetized substances are attached. This is a magnetic focusing device, which is designed so that it also produces the desired luminous line to eliminate the line structure.

In another known arrangement, one is used for additional magnetic focusing A coreless coil placed in the tube neck, which is oval-shaped to achieve a luminous line (wireless World, 1952, pp. 219-221). Because of the large stray field this coil is a large electrical Performance required.

It is also known (Austrian patent specification 189 661), a luminous line through two next to the To achieve tube neck diametrically arranged magnetic plugs, which magnetized perpendicular to the electron beam are. This arrangement can and can also be used with electrostatic focusing can be retrofitted because of their simplicity, but the magnetic plugs must be very precise adjusted because the position of the magnets is very critical.

This disadvantage is eliminated if, according to the invention, the magnetization direction of the permanent magnets or electromagnet lies parallel to the electron beam and if the magnets are to the tube neck have directional pole pieces.

Tests have shown that with the arrangement described, it is not necessary to align the magnets is. Rather, it is sufficient to shift and rotate the entire arrangement on the tube neck. Because of the pole pieces, small permanent magnets or electromagnets with low power requirements are sufficient the end.

Magnetic electron lens for reduction
the line structure in television receivers

Applicant:
Telefunken

Patentverwertungsgesellschaft mb H.,
Ulm / Danube, Elisabethenstr. 3

Named as inventor:

Friedrich Kratochvil, Hanover-Ricklingen

For a more detailed explanation, an exemplary embodiment is described below with reference to the drawing.

In Fig. 1 shows a cathode ray tube 1 with a cathode ray 3 in its tube neck 2 is generated, which is focused on the screen 4 by focusing means not shown here and to generate an image grid by deflection coils 5 in the vertical and horizontal directions over the Screen is distracted.

In the case of such cathode ray tubes, in order to achieve the greatest possible image sharpness, it is desirable to dimension the light spot as small as possible, so-called black-and-white jumps essentially to train distortion-free. With an increasing reduction in size of a luminous point, i. H. one Luminous spot of circular cross-section, but dark stripes appear between the lines The width becomes larger, the smaller the number of lines and the larger the screen. These dark lines are no longer annoying if the viewer is within a certain distance from the screen, but it is often desirable to make these dark lines disappear. This will be the case the arrangement according to FIG. 1 causes the cross section of the electron beam 3 essentially is dimensioned elliptically. Such an elliptical cross section is shown at 6. To achieve the elliptical cross section of the cathode ray 3 is a magnet arrangement 7, consisting of a Plastic body in which several cylindrical magnets 8 and 9 are embedded, their direction of magnetization runs parallel to the tube axis. Around

409 510/401

this arrangement? in a simple manner also afterwards To be able to apply to the tube neck, the plastic body is designed to be resilient by between the magnets, in addition to the bore surrounding the tube neck 2, there is an opening 14 (FIG. 1 and 2) is provided and the diametrically opposite side 10 of the body is slotted. Which The resulting slot 10 can be dimensioned with a more or less large width. Depending on the width of the dark lines, d. H. the field strength of the manete must depend on the size of the line spacing 8 and 9 can be changed so that the same arrangement for devices of different screen dimensions can be used. For this purpose there are one on each side of the plastic body, two or three recesses are provided, in which magnets can be inserted if necessary.

In Fig. 2, the arrangement 7 is shown enlarged. In this figure, a brass strip 11 is injected into the body 7 to increase the spring effect or poured. For devices that are exposed to vibrations, it can also be advantageous to attach a screw or clamp connection 12 to the slotted side of the body in order to Clamp body 7 on the tube neck. On both sides of the magnets are sheets of ferromagnetic material Material attached, which have the shape of pole pieces 13.

Instead of the permanent magnets 8 and 9 shown here, electromagnets can also be inserted into the plastic body 7 can be used, in which case the field strength can be easily changed. Such an arrangement also offers the option of supplying power to the electromagnets via one the outside of the housing arranged switch to operate to the viewer the opportunity give to make the stretching of the light spot to a light line arbitrarily. This particularly offers therefore advantages, because when viewed from a distance, the sharpness of the image improves becomes, while on closer inspection, the suppression of the line structure is often more desirable is.

It is also possible to make the magnets themselves adjustable by using cylindrical magnets magnetized in the direction of the radius and perpendicular to the tube axis. the cylindrical magnets are provided with pole pieces, which lie one behind the other in the direction of the tube axis, each half of the cylindrical magnets on the circumference and with the free one End are adapted to the tube neck. By turning the magnets, the size of the Lens field vary.

Claims (7)

Patent claims: 1. Magnetic electron lens for. Cathode ray tubes in television receivers, in which two diametrically arranged next to the tube neck Magnetic systems the light spot displayed on the screen to reduce or eliminate the line structure is stretched to a luminous line perpendicular to the direction of the line, characterized in that the direction of magnetization of the permanent magnets (8, 9) or the electromagnet is parallel to the electron beam and that the magnets for Pole shoes (13) directed towards the tube neck. 2. Electron lens according to claim 1, characterized in that the permanent magnets are cylindrical and are magnetized in the direction of their axis (Fig. 1,2). 3. electron lens according to claim 1 with electromagnet, characterized in that in the Circuit of the electromagnet is located on the outside of the receiver operable switch. 4. electron lens according to claim 1, characterized in that the magnets of one Plastic body are worn, which can be pushed onto the tube neck from the side is slotted on one side (Fig. 2). 5. electron lens according to claim 4, characterized in that the plastic body on the the side facing away from the slot has a recess for achieving a spring effect (Fig. 2). 6. electron lens according to claim 1, characterized in that the permanent magnets are cylindrical and are magnetized in the direction of their diameter and that their axis is perpendicular is arranged to the axis of the cathode ray tube. 7. electron lens according to claim 1, characterized in that the pole pieces (13) to the Tubular neck are adapted. Considered publications:
German utility model No. 1 793 797;
Austrian Patent No. 189,661;
Swiss patent specification No. 219 292. 1 sheet of drawings 409 510/401 2.64 ® Bundesdruckerei Berlin