US2602902A - Sweep amplitude control for magnetically deflected cathode-ray tubes - Google Patents

Description

July 8, 1952 G. 1.. HAUGEN 2,602,902

SWEEP AMPLITUDE CONTROL FOR MAGNETICALLY DEFLECTED CATHODEI-RAY TUBES Filed Feb. 14, 1950 FIG. 2

gwuc'ntov GLENN L. HAUGEN Patented July 8, 1952' SWEEP AMPLITUDE CQNTROL-FOR MAG-1 NETICALLY DEFLECTED. CATHODE-RAY TUBES Glenn-L. Haugen, Baltimore, -Md., 'assignor to I BendixAviation Corporation, T'0wson,Md., a.

corporation of Delaware Application February 14, 1950, Serial No. 144,139

This invention relates to'a simple and inex-. pensive means for the control of. the sweep amplitude of a cathode ray tube. It lends itself, particularly'to use for the control of thehorizontal width'ofthe picture of a television picture tube.

Necessity for such a width control means arises,. for example, in the manufacture .of television sets where it is desired to construct receiver assemblies which may be used for either of-two sizes of picture presentation. In such cases it is economical to utilize one horizontal deflection circuit for both picture sizes. This can be accomplished by the use of a coil and tuning slug but these components are comparatively expensive and their use entails extra wiring, an extra mounting hole in the chassis and a tap on the horizontal output transformer.

It is an object of the prsent invention to provide a sweep amplitude control means for magnetically deflected cathode ray tubes which is simple and inexpensive to manufacture and requires no circuit or chassis alteration for its use.

It is another object to provide such a control means which is readily accessible for adjustment from the rear of a television receiver.

It is a further object of the invention to provide such a control means the presence or adjustment of which does not affect the performance of the set other than with respect to the sweep amplitude of the cathode ray tube.

These and other objects of the invention are realized by a split metallic sleeve fitted around the neck of the cathode ray tube beneath the deflection coils and movable longitudinally of the tube to vary the amplitude of its deflection.

Referring now to the drawing:

Fig. 1 is a perspective view of a sleeve embodying the invention, and

Fig. 2 is a side elevational view of a portion of a cathode ray tube showing the sleeve of Fig. l in place on the neck thereof and showing the deflection and focus coils in section.

Referring more particularly to the drawing, Fig. 1 shows a cylindrical sleeve III, of thin sheet metal which may be either magnetic or non magnetic in character. The sleeve is provided with a longitudinal interruption H extending its full length.

In Fig. 2 the sleeve I is shown in place on the neck of a cathode ray tube l2 about which it fits snugly. It is shown as extending beneath the deflection yoke l3 for part of the latters length and as extending through and to the rear of the focussing coil I4 toward the base of the cathode ray tube.

5 Claims. (Cl. 313-.76)

tube. The interruption I I is necessary in order to prevent the sleeve from acting as a shorted turn for the deflection yoke.

The sleeve, if of non-magnetic material, is allowed to project to the rear of the focussing coil to permit it to be easily reached from the rear of the set for adjustment of its position along the neck of the cathode ray tube. It can easily be held in position by tape. A non-magnetic sleeve will not affect the action of the focus coil.

A non-magnetic material is preferred since it is more highly conductive. Aluminum is particuluarly suited for this device since it is light, inexpensive, highly conductive and easily worked.

The sleeve 19 is, of course, formed of a strip of sheet metal. If a lesser degree of amplitude control is desired the strip maybe narrower,so that it lies only on one side of the tube neck. In this case care must be exercised in positioning the strip with respect to its angular relationship to the horizontal deflecting coils, in order that the shape of the picture will not be distorted.

This simple device lends itself well to the selective control of the horizontal width of a television presentation since the horizontal circuits operate at 15,750 C. P. S. whereas the vertical circuits operate at C. P. S. At the higher frequency eddy currents are induced in the sleeve and they oppose the magnetic field of the horizontal deflection coils. Horizontal width can be varled by as much as 25 per cent by sliding the sleeve in or out of the yoke, with a negligible efiect on high voltage. The vertical circuits, operating at 60 C. P. S., are virtually unaffected.

An aluminum sleeve 3.25 inches in length and having a thickness of .005 inch has been found to give satisfactory results in a television receiver. These dimensions are, however, not to be regarded as limiting the invention, being given only by way of example.

What is claimed is:

1. The combination comprising a cathode ray tube, a magnetic deflection yoke positioned on the neck of said tube and a non-magnetic metallic strip extending longitudinally of the neck of said 3 tube, said strip extending betwen the neck of said tube and at least a portion of the Width of said yoke.

2. The combination comprising a cathode ray tube, a magnetic deflection yoke positioned on the neck of said tube and a metallic,-non-magnetic, longitudinally interrupted sleeve positioned on said neck and extending at least partly beneath said yoke.

3. In a cathode ray tube assembly comprising a cathode ray tube and a deflection coil yoke encircling the neck thereof; the combination therewith of a longitudinally interrupted, non-magnetic, metallic sleeve positioned on said neck and slidable therealong, a portion of said sleeve underlying said yoke.

4. In a cathode ray tube assembly comprising a cathode ray tube having a deflection coil yoke and a focus coil encircling the neck thereof; the combination therewith of a longitudinally interrupted, non-magnetic, metallic sleeve positioned on said neck and slidable therealong, a portion of said sleeve underlying said yoke, said sleeve extending beneath said focus coil and extending,

along said neck to a point between said focus coil and the base of saidcathode ray tube.

5. Means for controlling the sweep amplitude of a cathode ray tube having a magnetic deflection yoke surrounding the neck thereof; said means comprising a non-magnetic metallic sleeve having an interruption extending the full length thereof, said sleeve fitting around the neck of said tube beneath said yoke.

GLENN L. HAUGEN. REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,172,733 Federmann et al. Sept. 12, 1939 2,195,470 Roosenstein et al. Apr. 2, 1940 2,212,206 Holst et a1. Aug. 20, 1940 2,224,933 Schlesinger Dec. 17, 1940 2.3361337 Bedford Dec. 14, 1943 2,431,077 Poch Nov. 18, 1947 2,435,984 Spencer Feb. 17, 1948 2,433,359 Clapp Mar. 23, 1948 2,494,459 Torsch Jan. 10, 1950 2,500,623 Babbs Mar. 14, 1950 2,513,221 Webb June 27, 1950 2,563,525 Foster Aug. 7, 1951 2,569,343 1 Scull, Jr Sept. 25, 1951 FOREIGN PATENTS Number Country Date 462,683 Great Britain Mar. 12, 1937 472,165 Great Britain Sept. 13, 1937

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