US2172733A - Deflection coil - Google Patents

Description

SePt- 12, 1939 w. FEDERMANN r-:T AL v,2,172,733

D'EFLECTION COIL Filed MarOh 2, 1936 TTORNEY Patented Sept. 12, 1939 UNITED STATES PATENT OFFICE Heidenreich, Berlin,

Germany, assignors to Telefunken Gesellschaft fr Drahtlose Telegraphie m. b. H., Berlin, Germany, a corporation of Germany Application March 2, 1936, Serial No. 66,570 In Germany March 28, 1935 3 Claims.

This invention relates to electromagnetic deflection coil structures for cathode ray tubes, as used in particular for television, and in particular, where the windings of the coil are arranged over surfaces of cylinders or of spheres the axis of which coinciding with the tube axis.

Several structures in accordance with the invention will be described in the following whereby a series of features will be noted which are of advantage in a coil of the type mentioned.

Referring to the drawing:

Figs. 1 and 2 show one embodiment of my invention;

Fig. 3 shows a modification of the embodiment shown in Figs. 1 and 2;

Figs. 4 and 5 relate to damping means for the deflection coils;

Figs. 6 and '7 shows the combination of coil structures and damping means;

2 Fig. 8 shows one form of electrostatically shielding two sets of deflecting coils; and

Fig. 9 shows one form of electrostatic shield.

Figures 1 and 2 show a deflection coil for the cylindrical arrangement in cross section at right angle to the tube axis, as well as in a cross section along the tube axis. In both figures item I designates the glass vessel of the cathode ray tube, while Il and l2 are the upper and lower half of the coil. Both coils have rectangular 30 windings which can be so arranged that each deflection coil extends throughout one half of the circumference of the cylinder concentrically disposed to the tube axis. If the coil windings are arranged on cone surfaces, the single turn in this case is formed accordingly as a trapezoid.

The dellection coils may also be divided into several layers of turns which may be separately mounted on the tube, and within each winding layer the turns may be combined into winding packages such as designated by I3-I8 in Figure 3. The indivual winding packages are preferably wound into circular coils, then they are given a rectangular or trapezoidal shape and thereafter placed around the glass vessel of the tube. The beginning and the end of each package are so connected together that adjacent bundles of Wires follow each other in the sense of the current flow.

As compared with the hitherto known coils, the deflection coil as herein described has the advantage that almost the entire flux produced by the coil permeates the tube neck. In addition, the field within the tube neck has a homogeneity that is much greater than in case of the hitherto ordinary coil arrangement.

(Cl. Z50-157) In order to render the coil suited also for such purposes in which temporary free oscillations of the coil occur, a cylinder or cone of conductive material preferably of German silver is placed around the coil concentrically to the tube axis 5 and between the individual windings, or between coil and glass tube. Such conducting body which may for instance also be formed ci a carbon deposit, causes a damping of the partial oscillations carried out at higher frequencies at the free oscillation of the deflection coil, and which occur in a greater degree than the basic oscillation, i. e., that in which the entire coil participates. If the damping for the basic and partial oscillation is desired to differ to a still greater extent, the conducting body may be formed in such manner that it represents a short circuit ring only for such flux that is coupled to a part of the coil windings, or for a part of the flux coupled to all windings. The first mentioned eiect will be obtained for instance if the damping body is shaped in accordance with Figure 4 in the form of a collet, and the second eiect will be obtained with a shape according to Figure 5.

Even where the coil surrounds the entire tube body or almost the entire tube body, will it be possible to arrange a second coil for the deflection of the cathode ray in another direction, without the necessity of displacing the second coil in the direction of the tube axis. The cylindrical form of the coil even permits to arrange a second coil pair in a structurally especially simple manner.

Furthermore, it was found to be advisable to shield the two coils electrostatically against each other. This may for instance be done by placing between the two coils assigned to different directions of dellection, an open, and grounded winding of insulated wire, whose winding planes 40 are at right angles to the tube axis. This winding is preferably placed on. a card board cylinder accommodated between the two coil pairs. The two coils may also be shielded electrostatically against each other in that one of the two 45 coils or its individual winding packages are Wound with a metal band preferably of aluminum.

Figure 6 shows the coil windings arranged on a cone surface, and the position of the damping 50 bodies I9, 20 corresponding to Figure 5 in combination with the glass vessel of the tube. It should furthermore be noted that if necessary, the coils will in part be arranged on the cylindrical tube neck and in part on the part of the 55 tube forming the frustrum of a cone such as is shown in Figure 7. In this latter gure the metal bodies I9, 20 have been omitted for the sake of simplication.

Figure 8 shows a cross-section drawing of a neck of a cathode ray tube with two sets of de fleeting coils, Il, I2, and 3|, positioned in register with each other, and mutually perpendicular to each other, and positioned around the tube l0. Between the two sets of coils is placed an electrostatic shield 33 which is grounded at one end by the connection 37. The coils are mounted over light annular rings 35 to provide optimum damping, as described above. The shield 33 is shown in Fig. 9 and comprises a single link of wire wrapped helcally in one plane and with one end grounded. It is shown mounted around the tube l0.

It will be apparent that many modications of the invention may be made by those skilled in the art without departing from the spirit of the invention which we claim.

What we claim is:

1. In a cathode ray beam deflection system, a

cathode ray tube having a cylindrical wall, two separated thin annular metallic rings supported in register upon said wall, electromagnetic deiiecting coils positioned upon the rings, and means within the cathode ray tube to direct the cathode ray beam through the rings.

2. In a cathode ray beam deflection system, a cathode ray tube having a cylindrical wall, a thin metallic collet supported upon the wall, electromagnetic deecting coils positioned upon the collet, and means within the tube to direct the cathode ray beam through the developed collet.

3. In a cathode ray beam delecting system, a cylindrical supporting wall, an isolated ring of conducting material supported upon the wall, a plurality of magnetic coils positioned upon the conducting material whereby the coils are critically damped to prevent free oscillations arising therein, and an electrostatic shield between the coils.

WOLFGANG FEDERMANN. ROBERT ANDRIEU. FRANZ HEIDENREICH.

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