US2452388A - Electromagnetic system - Google Patents

Description

Get. 26, 1948,

F1188 Sept. 20, 1944 A. v. NICHOL 2,452,388

tmncmomausnc sYs'TmI 2 sham-sheet 1 INVENTOR.

44% lax-6M I Oct. 26, 1948. A. v. NICHOL 2,452,338

ELECTROMAGNETIC syswrm Filed Sept. 20, 1944 2 Sheets-Sheet 2 INVENTOR.

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Patented Oct. 26, 1948 ELECTROMAGNETIC SYSTEM Arthur V. Nichol, Elkins Park, Pa., assignor. by mesne assignments, to Philco Corporation, Philadelphia, Pa., a corporation of Pennsylvania Application September 20, 1944, Serial No. 555,022

3 Claims. 1

The present invention relates to deflecting means for electric beam indicating devices and concerns particularly deflecting systems for cathode ray oscilloscopes and the like.

An object of the invention is to provide improved means for translating mechanical motion into deflection of a stream or ray of electrifled particles or an electronic beam such as in cathode ray tubes. I

In radio locator and like systems, where ultrahigh-frequency search equipment is necessary,

. it is customary to translate an antenna or scanner motion into a synchronized deflection pattern on the signal indicating device. As is known, the synchronization of an antenna motion with a deflection pattern is usually accomplished by means ofpotentiometers or Selsyn controllers driven by the antenna, and the electrical information provided by these devices is converted into suitable potentials that are applied to the electrostatic deflection plates of the cathode ray tube or convertedinto current values that are applied to coils wound on yoke structures that supply magnetic flux for deflecting the beam of the magnetic type cathode ray tube. conventional devices, commonly used, are bulky, heavy, expensive, subject to inaccuracies, and generally require the use of amplifying or modifying circuits, there necessitates a means for synchronizing an ante na motion with the sign l deflection pattern which exercises considerable care in'avoiding the undesirable objections mentioned above.

It is, therefore, the primary'object of the present invention to provide a novel means whereby an antenna or scanner motion may be synchronized with the deflection pattern on the signal indicating tube.

Since these Another object of the present invention is to 2 fleeting the electron beam vertically and a vertical changing flux density to produce a horizontal deflection of the beam. As the spot on the screen of the signal indicating device sweeps across the screen vertically, a means which is well understood by those skilled in the art, may be provided whereby the range of an object from a craft may be determined. Said spot also moves horizontally during said vertical sweep according to a changing vertical flux density and flux polarity which is synchronized with the antenna motion, thus providing a means which the invention sets forth, for determining the direction of an object from a craft. Said pattern and other types of patterns have had one flux density for deflecting the beam synchronized with the antenna motion as hereinbefore mentioned. In accordance with the present invention, a novel mechanical device is provided for simplifying the method of producin the vertical flux density desired.

In carrying out the present invention in a preferred embodiment thereof, a mechanical linkage is provided which transmits the motion of the type which is, by definition, the horizontal measuremeiit in degrees to the right or left of a reference representing the direction a craft is pointing, i. e., when an antenna (parabolic reflector) is scanning in the direction that a craft is pointing, the azimuth reading is zero degrees. For the zero azimuth reading, the permanent mag net, synchronized with the azimuth motion of the antenna, is so positioned between the pair of indicating device, used at ultra-high frequency I in radio locator or radar and the like systems,

soft iron shoes, hereinbefore mentioned, that the vertical flux density between said shoes is zero. Hence, an azimuth motion of the antenna is effectivein producing a rotational movement of said magnet which determines the desired changing flux density and flux polarity between said shoes for deflecting the beam horizontally. By providing a degree scale on the horizontal boundary of the deflection pattern corresponding substantially to a sine function representing the changing flux density and flux polarity, as the antenna sweeps the desired sector, the direction of an object from a craft may be determined.

\ I accasae mconnectionwiththepresen' tin'ventioflht m I is provided on the signal indicating tube a rectangular deflection pattern comprising boundaries deri ed by two flux densities and their rates of change. The flux density for determining the horizontal boundaryof said pattern is derived by conventional means by passing a current. which is proportional to a saw-tooth sweep voltage. through coils wound on yoke structures onthe neck of the signal indicating device, thus supplying the necessary changing flux density for deflecting the electron beam vertically. This deflection oi the beam determinesa sweep for measuring the distance of an object from a craft. Considering the antenna scanning a horizontal sector of'150", i. e., 75 to the left of reference v 7 (direction craft is pointing) and back, then 75 to the right of reference and back, there is developed a vertical changing flux density and flux polarity between the pair of iron shoeswhich are placed across the neck of the signal indicating tube,.by the rotational movementof a permanent magnet causing the electron beam, as it sweeps across the screen vertically, to be deflected horizontally. thus providing the vertical boundaries of the desired rectangular pattern tobe synchrosaid crank by a convenient clamping device I2. so as ,to occupy'space between the ends lb and lb of the members la and which form a second pair oi pole shoes. At the end of the mechanical izontal tension in the vicinity of crank II as the nized with the azimuth motion of the antenna.

The invention will be better understood by reference to the drawings accompanying the speciflcation in which:

Fig. 1 shows a conventional antenna reflector system in conjunction with a cathode ray tube indicator having a horizontal deflection system synchronized with antenna motion to represent one embodiment of the invention.

Fig. 2 is a two dimensional geometrical illustration of the horizontal sector through which the antenna sweeps.

Fig. 3 illustrates a few trace moving from right to left across the screen of the signal indicating tube as the antenna, which is synchronized with said movement. scans the desired sector from left to right; and I Fig. 4 shows a few positions of the vertical trace moving from left to right across the screen of the signal indicating tube as the antenna, which is synchronzed with said movement; scans the desired sector from right to left. M

positions of the vertical Referring to Fig. 1, it may be observed that the portion of a radar system to which the present invention is applied comprises the conventional antennarefiector system I which is driven through a horizontal sweep motion (sector scanning) by a suitable driving mechanism 2. A conventional signal indicating tube (magnetic type cathode ray .tube) is represented by thereference character 3. Conventional vertical deflecting coils for the tube are represented at 4. Such devices are well known in the art, and since they are not a part of the present invention, it is deemed unnecessary to describe them in detail. The electronic beam is represented by a dotted line So.

Referring again to Fig. 1, the cathode ray tube 3 is provided with a pair of U-shaped soft iron members 5a and So having a pair of parallel ends forming pole shoes 5 and 6 which'members are separated by a suitable spacer 1 so that said pole shoes may be horizontally mounted across the neck of .tube 3. A stand 8, which has one end mounted to the chassis (not shown) and the other end suitably fastened to the iron members Ia and 8a in the vicinity of said spacer. holds the membars in position. A bushing suitably placed in spacer 1, serves as the center of rotation. for a crank I0. A permanent magnet I I is attached to parabolic reflector sweeps sector.

The bending of the members 5 and I into U-shapes greatly weakens the flux density in the vicinity of the U-portion of said members and provides for greatest flux density between the pole shoes Ib andlb in the vicinity of the permanent magnet II and between the poleshoes 5 and 8 straddling the neck of tube I. In addition, the

U-shaped portion of said members effectively isolates the stray magnetic field of. said magnet from interfering with the vertical flux density between the portions of said shoes which are placed across the neckof the signal indicating tube 8.

In the preceding discussion, reference has been made to. the U-shape of the soft iron members 5a and in. Such a shape has been found con.- venient, but it will be evident that other designs affording generally similar results may be employed.

- In using the term soft-iron" in the description and claims, I mean to include any suitable material having the properties of sort-iron such as high permeability and low coercive force and I do not mean to exclude alloys or substances havin such properties although containing little or no iron.

The synchronization of the antenna motion with the flux density which determines the position of the beam to that provides the indication of the vertical boundary of the rectangular deflection pattern on the signal indicating tube 3, can best be understood by referring to Fig. 1. when the parabolic reflector I is scanning in the direction a craft is pointing (this position of the reflector is represented by line I8 in Fig. 2). the length of linkage I! (Fig. l) is such that crank I0 (Fig. 1) may be easily rotated about its center of rotation (bushing O) and the permanent ma net II is arranged in. a horizontal position between the shoes 5 and I as shown in Fig. 1. With the reflector and the permanent magnet in these positions mentioned above, the vertical trace would be centered on the screen of, the signal indicating tube as shown by line I 8 in Fig. 3. As the reflector scans the portion of the sector indicated by the arrow 2. (Fig. 2), the crank Il (Fig. 1) rotates in the. direction of the arrow 2|. This movement of said crankrotates the permanent magnet II in the direction of the arrow 22 (Fig. l) The magnet II isobviously in inductive relation to the flux conducting members la and 6a. With the polarity of said magnet as shown, there is derived an increasing flux density 23 between the ends of the soft-iron shoes I and 6 which are placed across the neck of tube 3 (Fig. 1) This steadily increasing flux density, as the magnetic rotated toward its maximum vertical position. inconiuncnion with the characteristics of theelectron beam to deflects the beam horizontally as said beam sweeps across the screen through its desired by the dashed arrow 25 (Fig. 2), the crank ll reverses direction as shown by arrow 26, the permanent magnet H rotates in the direction of arrow 21, and the flux density 23 steadily decreases allowing the vertical trace to approach the center of the screen as shown by lines 23 (Fig. 4). As the antenna continues scanning as shown by arrow 29 (Fig. 2), crank and said magnet rotate in.

the direction of arrows 30 and 3| respectively. This direction of scanning of said antenna reverses the flux density polarity as shown by the dashed arrows 32 (Fig. 1), and as said magnet continues rotating toward its maximum vertical position, the electron beam continues moving to the right as shown by lines 33 (Fig. 4); when the antenna recedes to zero degree azimuth, as shown by the dashed arrow 34 (Fig. 2) the crank and magnet will rotate in the direction illustrated by arrows 35 and 38 respectively, and the flux density 32 will steadily decrease allowing the beam, as it sweeps vertically across the screen to move toward the left as shown by lines 37, thus completing one cycle of operation which will-now repeat.

Although the invention has been described with particular reference to an azimuth motion of the antenna, it will be understood that the invention is not limited to the specific disclosure, but only scope or the appended claims.

laim:

1. A cathode ray beam deflector comprising in combination a pair of U-shaped soft iron yoke pieces with parallel ends, one pair of which ends is adapted to tilt over the neck of a cathode ray tube, and a permanent magnet rotatably mounted between the other pair of ends of said yoke pieces for varying the magnetic flux between the first pair of ends in response to rotation of the magnet.

2. An electronic motion indicator comprising in combination with a movable device, the position of which is to be indicated, an electronic beam device having a neck through which an electron beam is projected. stationary magnetic flu; conductin means having a pole shoe on each the flux crossing the. neck of said electron beam device.

ARTHUR. V. NICHOL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,535,329 MacGregor Apr. 28, 1935 2,102,421 Kuehni Dec, 14, 1937 2,130,913 Tolson Sept. 20, 1938 2,185,307 Skellett July 11, 1939 2,224,933 Schlesinger Dec. 17, 1940 2,227,080 Goldsmith Dec. 31 1940 2,231,929 Lyman Feb. 18, 1941 2,261,309 Stuart Nov. 4, 1941 2,263,377 Busignies et al.'.. Nov. 18, 1941 2,275,974 Mathes Mar. 10, 1942 40 2,314,302 Ziebolz Mar. 16, 1943 2,355,727 Holters Aug. 15, 1944 2,360,751 Ziebolz Oct. 17, 1944 2,400,814 Dodds May 21, 1946 FOREIGN PATENTS Number Country Date 494,283 Great Britain Oct. 24, 1938 497,147 Great Britain Dec. 9, 1938 546,202 Great Britain July 2, 1942 side or said neck, a permanent magnet in inductive relation to said magnetic flux conducting means, a rotatable support for said magnet for varying the magnetic flux crossing said neck in response to movement of the permanent magnet, a crank on said support, and a linkage between said crank and the movable device, the position of which is to be indicated.

3. A search indicator comprising in combination a scanner, an electron beam device having a neck through which an electron beam is projected, stationary magnetic flux conducting means having a pole shoe on each side of said neck, a permanent magnet mounted in inductive relation to said flux conducting means, a rotatable support for said magnet having a crank, and a linkage between said crank and said scanner whereby the position of said scanner determines the position of the magnet and thereby adjusts

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