US2470875A - Storage tube - Google Patents

Description

May 24, 1949. R. L. SNYDER, JR

STORAGE TUBE Filed April 12, 1946 Patented May 24, 1949 STORAGE TUBE Richard L. Snyder, Jr., to Radio Corporation of Delaware New York, N. Y., assignor of America, a corporation Application April 12, 1946, Serial No. 661,684 13 Claims. (Cl. Z50-150) This invention relates to cathode ray tubes and is particularly useful in storage tubes such as disclosed in my application led July 24, 1945, Serial No. 606,812, though it is not limited thereto since it can be applied to various types of tubes in which the electrons proceed from the target to multiplier units arranged around the axis of the gun. In my said application, electromagnetic focusing and deecting means are employed and the construction has operated very satisfactorily, but the weight of the tube unit and the power requirements are more than desired in certain uses.

It is an object of this invention to provide a storage tube of reduced we'ght and power requirements.

Another object of the invention is to arrange the electrodes and other parts so that electrostatic focusing and deflection of the cathode beam may be used with multiplier units arranged around and in the vicinity of the gun.

Other objects of the invention will appear in the following description, reference being had to the drawing, in which:

Fig. 1 is a longitudinal central section of a cathode ray tube employing the invention.

Fig. 2 is a partial section of the gun and deecting electrodes with the surrounding shield, being taken on the line 2-2 of Fig. 3.

Fig. 3 is an end view of the parts shown in Fig. 2.

Fig. 4 is a section taken on the line 4 4 of Fig. 2.

Referring to the drawing, the tube comprises an evacuated glass or other suitable envelope I containing a gun at one end and a target 2 at the other end. The gun consists of an indirectly heated cathode 3 inside the grid 4 positioned adjacent the rst anode 5. The grid has the usual aperture 6 and the end of the first anode adjacent the grid has a rst aperture 1. The cathode, grid and rst anode are of tubular metal construction, as usual. The first anode has a second dening aperture 8 adjacent the end remote from the grid (see Fig. 2). Close to and spaced from this end of the rst anode is positioned the second anode 9, also of tubular metal construction, but having a cylindrical end I of reduced diameter. The grid, the first anode and second anode are mounted together by means of four mica strips Il sectioned in solid black in Fig. 1. These have holes I2 therethrough. There should be two or more holes in each strip for each electrode. A thin metal ribbon I3 is placed lengthwise over the mica strips I I, over the cylinder of grid 4, and are welded through the holes I2 to the underlying cylinder.

Four similar metal strips I4 and I5 are welded through the holes I2 to the first and second anodes, respectively. The strips of the grid, first anode and second anode are, of course, spaced so as not to short these electrodes. All of the mica strips II are of such width as to center the electrodes within a shield tube I 6, as will be made clear by Fig. 4.

A metal disc I1 is Welded to the end of the second anode. This disc is of such diameter as to t the inside diameter of shield tube I 6, as the second anode and shield have the same applied potential and hence they need not be insulated from each other. The cylindrical end I0 and the disc I1 have appropriate apertures I8 for passage of the cathode beam.

A mica disc I9 ts inside shield tube I6 and against disc I1. A metal disc 20 is sandwiched between two mica discs 2| and 22 and these three discs are spaced from discs I1 and I9 as shown in Fig. 2. Metal discs I1 and 20 and mica discs I9, 2l and 22 have four holes 23 equally spaced around the circumference and four wires 24 snugly t in these holes to position the discs circumferentially in respect to the second anode. The four wires are welded to the disc I1 and cross wires 25 are welded to the wires 24 against mica disc I9 and against mica. discs 2l and 22 to hold them against metal discs I1 and 20, respectively. The metal discs I'I and 20 have eight holes 26 preferably arranged so that all the holes 23 and 26 are equally spaced around the circumferences. These eight holes are preferably larger than the holes 23, as indicated in Fig. 3. The mica discs I 9, 2l and 22 have four holes 21 coaxial with and smaller than four of the holes 26 and wires 28, 29, 30 and 3|, which may be smaller than wires 24, snugly fit the holes 21 and extend through the aligned holes of all ve discs and sufficiently beyond to support the horizontally deecting plates 32, 33 and are welded to wires 28, 29 and 30, 3l, respectively. The mica discs I9, 2l and 22 likewise have four holes 34 coaxial with the remaining holes 26 in the metal discs I1 and 20 and four wires 35, 36, 31 and 38 snugly fit the holes 34 and extend through the aligned holes of the live discs. Vertically deflecting plates 39 and 40 are positioned between mica discs I9 and 2l and are welded to wires 35, 38 and wires 36, 31, respectively.

With the deecting units assembled as described, the plates are individually insulated from each other and from the second anode and shield I6. Insulated wires 4|, 42 and 43, 44 may extend between the shield tube and be Welded to appropriate ones of the sup- I6 and the anode cylinder porting wires of the deflection plates for supplying voltage thereto.

The grid and the first and second anodes are properly positioned and supported within the shield tube by the arrange-ment described and the cathode may be supported within the grid in any well-known manner. This is indicated in Fig. 1 by the cathode extending through insulation member 45 held in the end of the cylinder of grid 4I. The shield I6 is flanged at 45a and is welded to the base of a cup-shaped gun mount 45h that may be supported in the envelope in any known Way, for example, as disclosed in the application of Stanley V. Forgue, led January 28, 1946, Serial No. 643,925 now Patent No. 2,441,315, issued May 11, 1948.

The usual wall coating 46 on envelope l extends from adjacent the end of shield tube I6 toward the target, as shown in Fig. 1. A focusing electrode 41 is positioned at the gun end of the wall coating and extends over the end of shield tube i6. First, second, third, fourth and fifth pin-wheel multiplier stages 48 to 52 and sixth multiplier stage 53 and collector 54 are positioned over the shield tube. These multiplier stages and collector are fully described in the application of Paul K. Weimer, led September 16, 1944, Serial No. 554,494, now Patent No. 2,433,941, issued January 6, 1948, and reference is made thereto for information of all the details thereof. It may be said briefiy, however, that the rst to fth stages each consist of a plurality of slanting vanes 55 somewhat like the blades of an electric fan. These are appropriately mounted in metal frames 56 in the front of which are mounted ne mesh screens 51 to shield the secondaries emitted by the Varies from the preceding potentials. It is preferable to make alternate dynodes with the blades slanting in opposite directions, as indicated in the partial section of stages 4B and 49. The final dynode in stage 53 may be a metal disc 58, as the secondaries emitted thereby are attracted directly to the collector 59, which may be a fine mesh screen like the screens 51. There may be any desired number of multiplier stag-es, The six stages shown are given merely by way of example. The target 2 may be an aluminum cup with a convex surface extending toward the gun. The cup may be anodized to form an oxide coating 60 on the convex side and a screen 6| is stretched over the oxide surface, as disclosed in my said application. A focusing ring 62 is placed adjacent the screen 6l. The various electrodes may have suitable voltages, such as those given on the drawing. rlhe negative and positive values are below and above ground, respectively, which is the potential of the screen 6I. The voltages of the grid and rst anode will, as generally understood, be adjusted for good focus on the target and the focusing ring electrodes 41 and 62 are adjusted for good focus on the first multiplier stage 48 of the secondary electrons emitted by target 2 upon impact of the beam thereon. The voltages of the various electrodes may be varied, but those given on the drawing will be found satisfactory.

The separate parts of the multiplier stages and collector may be assembled in frames in any way, for example like that disclosed in the application of Stanley V. Forgue, filed February '1, 1946, Serial No. 646,075, now Patent No. 2,460,381, issued February 1, 1949, and the multiplier, gun mount and focusing rings may be mounted as in the last-mentioned application or in any other Way.

The horizontally and vertically deflecting plates may be connected to saw-tooth voltage generators, not shown, of appropriate line and frame scansion frequencies, or to any other type of deflecting potentials required by the specic application.

My improved storage tube may be used wherever signals are to be stored and utilized at a later time. The storage time will, of course, depend upon the particular use of the tube and may vary from a fraction of a second to minutes, or even hours if desired. The change from storage condition to discharge or utilization condition may be by hand control or semior entirely automatic, as described in my application led June 20, 1945, Serial No. 600,498, now Patent No. 2,454,410, issued November 23, 1948.

Before describing the way in which storage of signals is secured, it will first be advisable to explain the effect of the scansion of the high velocity beam over the oxide target 60 with no signal being applied to the metal part 63 of the target cup 2. The potential of the oxide target surface 60 may happen to be positive, negative, or equal to the potential of the screen 6I and ground. For the moment, let it be assumed thatthe oxide coating is positive with respect to the screen. As the high Velocity beam is scanned over the oxide coating, secondary electrons will be bombarded therefrom at a greater than unity ratio. It is desirable to have the secondary emission be two or three times as great as the number of electrons landing from the beam. Whether these secondary electrons, however, eventually escape from the oxide surface depends upon the relative potential between the oxide surface and the screen 6l. Since it has been assumed that the oxide surface is positive relative to the screen, the secondaries will not escape but will return to the oxide surface. This means that the target surface is collecting the negative electrons of the beam and losing none from secondary emission. Therefore, the surface, upon impact of the beam, will be reduced to the potential of the screen 6 I. At this point just as many electrons will leave the oxide surface as are added to it from the beam. Scansion of the beam over the oxide surface thus brings its potential to that of the screen through a net gain of electrons if it is positive to the screen, or through a net loss of electrons if it is negative thereto, and the elemental areas will stay at these relative potentials unless some extraneous potential is applied thereto.

While the improvement may be applied to various uses, the operation in a coherent pulse type of radar system will now be explained by way of example.

In the known coherent p-ulse radar system, the signal pulses are transmitted at the beginning of each line scansion at the peak of the saw-tooth wave controlling this scansion. Echoes from both moving and stationary objects are received and impressed on the dielectric target in certain phases of the scansion, depending upon the distance of the objects from the transmitter-receiver. In most uses and in war work, particularly, the reflections or echoes from stationary or fixed objects, such as mountains, are not only 0f no interest, but they also clutter up the desired record of echoes from moving objects, such as airplanes, and make it difficult to determine which of the signals represent a moving object. With fixed objects the successive echoes arrive at the signal plate 63 always in the same phase of the.

line scansion, because their distance from the transmitter-receiver does not vary and the amplitude is constant. The echo signals from moving objects, however, vary -rapidly in amplitude, due to the well-known Doppler eifect, and slowly change in phase due to their varying distance from the transmitter-receiver. This means that if an echo signal from a fixed object is impressed on the signal plate S3 when the beam in one scansion is on a certain elemental area of the target, the same signals from that same xed object will be impressed on that elemental area and will have the same amplitude as the preceding signals. On the other hand, successive trains of echoes from moving objects will produce signals of varying amplitude when the beam is on a particular elemental area, because of the Doppler eiect.

Suppose trains of echo signals from a mountain peak are constantly arriving while the beam is on the nth elemental area of a scanned line. The signal potential will be impressed on the entire signal plate S3 and the potential of the entire dielectric target 60 will be proportionally altered, say raised above the potential of screen 6I. The nth area will therefore receive electrons from the beam in excess of emitted secondaries suicient to bring the surface down to the potential of the screen. As the beam leaves the elemental area n, the signal potential ceases to be impressed on signal plate 63 and the potential of the dielectric surface, except area n, drops down to screen potential. The elemental area n drops in potential as far below the potential of the screen El as it was raised above it by the signal. Absence of signals will be assumed until the beam reaches the mth area, when an echo signal of positive potential, say, from a moving object, is impressed on signal plate 63. The potential of all areas of the surface of the target, including area n, will again be altered by the signal. When the beam leaves the mth elemental area, the entire dielectric drops down to the potential of screen 6I except the elemental areas n and m, which drop as far below the screen in potential as they were raised above it by their respective signals when the beam was on those areas. The signal is thus recorded on the scansion described.

On the next scansion by the beam, it will nd elemental area n just as far below the screen potential as the signal potential of the wave train can raise it above that potential, because the signal is identical with that previously impressed on this area. Thus, the signal from the fixed object raises the potential of elemental area n up to the potential of screen 6|. Therefore, the electrons from the beam landing thereon release secondaries in a one-to-one ratio to the beam electrons, so that the electron stream passing to the multiplier or to the collector screen is not modulated. When the beam reaches the mth area, the signal arriving from the moving object has a different amplitude, because of the Doppler eiect. The beam nding the area m below the potential of screen 6| bombards a suiiicient excess of secondary electrons from its surface to bring the potential back to that of screen 6l. Thus, a signal is produced by an increase in the number of returning electrons.

It will thus be seen that with my invention the use of radar systems in operations over or near land surfaces has been enormously increased in eiectiveness, due to the substantial elimination of signals from stationary objects, leaving only those from moving objects which it is desired to identify and locate.

In radar systems the antenna is usually rotated to survey the entire horizon for echoes from objects. Since the radiation pattern of present directional antennas has material and variable breadth, signals from objects will vary with the eld strength of this pattern. The received signals from fixed objects in one scansion may therefore have different amplitudes from those of the previous scansion. Echoes from xed objects thus tend to increase in amplitude from scansion to scansion as the center of the radiation pattern approaches them and to decrease from scansion to scansion as the center of the radiation pattern moves away from them. Since this change in amplitude is unidirectional over a number of radar cycles, the dilTerences passed by the storage tube are all in the same direction. The output of the storage tube will therefore have a very slowly changing pattern of the differences, which can be removed by passing the signals through a second storage tube in cascade. That is, the output of one tube may be applied to the input signal plate of another tube. Since the small output pulses of the rst tube will have substantially constant phase and amplitude for any two successive line scansions for fixed objects, it will be apparent that the echoes from such objects will not produce signals. In the cascade arrangement, however, the echoes from moving objects Will produce signals in the second tube, since they are of varying amplitude in the output of the first tube.

The improved storage tube may be used in various other ways where storage of information is desired. Signals may .be impressed on the signal plate while the beam scans a predetermined pattern over the target. The signal and beam may then be shut off, leaving the information stored in the target. At any desired later time the beam may be turned on and, ywith no new signals impressed on the signal plate, scanned over the pattern so that the signal impressed during the iirst scansion will be taken oit by the subsequent scansion. As is evident from the described method of operation, recorded signals may be combined with new signals, enabling one to use the tube for carrying out complex operations by suitable combinations of signals.

It will `be apparent that when signals are recorded, the beam is modulated to the same extent as when the signals are taken off in a subsequent scansion, but in the opposite sense, and either or both modulations may be utilized when desired.

I claim:

l. A cathode ray beam storage tube comprising an evacuated envelope containing a gun, a target having a plurality of mutually insulated elemental areas, an electron multiplier between said gun and said target, a screen yadjacent and in front of said target adapted to control secondary electrons .bombarded from said target by said cathode ray beam, a plate capacitatively vassociated with said target for :applying successive signal potentials simultaneously to :all of the elemental areas of said target, means for electrostatically scanning said beam over said elemental areas :and means for electrostatically focusing on said multiplier the electrons escaping from said target. l

2. A cathode ray beam storage tube comprising an evacuated envelope containing a gun, a target having a plurality of mutually insulated elemental areas, an electron multiplier between said gun and said target, a screen adjacent and in front of said target adapted to control secondary electrons bombarded from said target by said cathode ray beam, a plate capacitatively associated with said target for applying successive signal potentials simultaneously to all `of the elemental areas of said target, means for electrostatically scanning said beam `over said elemen- .tal areas and means for electrostatically focusing the beam electrons on said target.

3. A cathode ray beam storage tube comprising an evacuated envelope containing a gun, a target having a plurality of mutually insulated elemental areas, an electron multiplier between said gun and said target, a screen adjacent and in front of said target adapted to control secondary electrons bombarded from said target by said cathode ray beam, a plate capacitatively associated With said target for applying successive signal potentials simultaneously to all of the elemental areas of said target, means for electrostatically scanning said beam over said elemental areas and means for electrostatically focusing the beam electrons on said target and the electrons escaping from said target on said multiplier.

4. A cathode ray beam storage tube comprise ing an evacuated envelope containing a gun, a t-arget having a plurality of mutually insulated elemental areas, a screen adjacent and in front of said target adapted to control secondary electrons bombarded from said target by the cathode ray beam, a plate capacitatively associated ywith said target for applying successive signal potentials simultaneously to all of the elemental areas of the target, means for electrostatically scanning said beam over said elemental areas, a metal cylinder around said gun and said last mentioned means, an electron multiplier around said cylinder and means for electrostatically focusing on said multiplier the electrons escaping from said t-arget.

5. A cathode ray beam storage tube comprising an evacuated envelope containing a gun, a target having a plurality of mutually insulated elemental areas, 4a screen adjacent and in front of said target adapted to control seconda-ry electrons lbombarded from said target by the cathode ray beam, a plate capacitatively associated with said target for applying successive signal potentials simultaneously to all of the elemental areas of the target, means for electrost-atically scanning said beam over said elemental areas, a metal cylinder around said gun and said last mentioned means, an electron multiplier around said cylinder and means for electrostatically focusing the beam electrons on said target.

6. A cathode ray beam storage tube comprising an evacuated envelope containing a gun, a target having a plurality of mutually insulated elemental areas, a screen adjacent and in front of said target adapted to control secondary electrons bombarded from said target by the cathode ray beam, 'a plate capacitatively associated With said target for applying successive signal potentials simultaneously to all of the elemental areas of the target, means for electrostatically scanning said beam over said elemental areas, a metal cylinder around said gun and said last mentioned means, an electron multiplier around said cylinder and means for electrostatically focusing the beam electrons on said target and the electrons escaping from said target on said multiplier.

'7. A cathode ray beam storage tube comprising an evacuated envelope containing a grid cylinder, a cathode supported within said grid cylinder, a

first anode cylinder spaced from said grid cylinder, a second anode cylinder spaced from Said iirst anode cylinder, all said cylinders being coaxial, electrostatic orthogonally disposed deiiecting plates, an open-end shield cylinder surrounding said cylinders and said plates, a target spaced from the open end of said shield cylinder, a screen adjacent the front surface of said target adapted to control secondary electrons bombarded from said target by the cathode ray beam, an electron multiplier positioned around said shield cylinder adapted to attract electrons escaping from said target and means for electrostatically focusing the escaping electrons on said multiplier.

8. A cathode ray beam storage tube comprising an evacuated envelope containing a grid cylinder, a cathode supported Within said grid cylinder, a nrst anode cylinder spaced from said grid cylinder, a second anode cylinder spaced from said first anode cylinder, all said cylinders being coaxial, electrostatic orthogonally disposed delecting plates, an open-end shield cylinder surrounding said cylinders and said plates, a target spaced trom the open end of said shield cylinder, a screen adjacent the front surface of said target adapted to control secondary electrons bombarded from said target by the cathode ray beam, an electron multiplier positioned around said shield cylinder adapted to attract electrons escaping i'rom said target and means for electrostatically focusing the beam electrons onsaid 'target and the escaping electrons on said multiplier.

9. A cathode ray beam storage tube comprisinder, a cathode supported Within said grid cyl'- inder, a first anode cylinder spaced from said grid cylinder, a second anode cylinder spaced from said first anode cylinder, all said cylinders being coaxial, electrostatic orthogonally disposed defiecting plates, an open-end -shield cylinder surrounding said cylinders and said plates, a target spaced from the open end of said shield cylinder,

a screen adjacent the front surface of said target adapted to control secondary electrons bombarded irom said target by the cathode ray beam, an electron multiplier positioned around said shield cylinder adapted to attract electron-s escaping from said target and means for electrostatically ocusing the beam eiectrons on said target.

ll). A cathode ray beam storage tube comprising an evacuated envelope containing a grid cylinder, a cathode supported within said grid cylinder, an anode cylinder spaced from said grid cylinder, said cylinders being coaxial, electrostatic deflectlng plates providing orthogonal deflection, an open-end shield cylinder surrounding said other cylinders and plates, a target spaced from the open end of said shield cylinder, a screen adjacent the front surface of said target adapted to control secondary electrons bombarded from said target by the cathode ray beam, an electron multiplier positioned around said shield cylinder adapted to attract electrons escaping from said target and a pair or spaced electrostatic rings between said target and said multiplier and outside said shield cylinder for focusing the escaping electrons on said multiplier.

ll. A cathode ray beam storage tube comprising an evacuated envelope containing a grid cylinder, a cathode supported within said grid cylinder, a rst anode cylinder spaced from said grid cylinder, a second anode cylinder spaced from said rst anode cylinder, al1 said cylinders being coaxial, electrostatic deiiecting plates providing orthogonal deection, an open-end shie1d cylinder surrounding said :other cylinders and plates, a target spaced from the open end of said shield cylinder, a screen adjacent the front surface of said target adapted to control secondary electrons bombarded from said target by the cathode ray beam, an electron multiplier positioned around said shie1d cylinder adapted to attract electrons escaping from said target and a pair of spaced electrostatic rings between said target and said multiplier and outside said shield cylinder for focusing the escaping electrons on said multiplier.

12. A cathode ray storage tube compri-sing an evacuated envelope containing a grid cylinder, a cathode supported within said grid cylinder, an anode cylinder spaced from said grid cylinder, said cylinder being coaxial, electrostatic deflecting plates, a plurality of insulation strips extending axially of said cylinders and outside thereof, means for securing said insulation strips to said cylinders, a shield cylinder surrounding the other cylinders and said plates, said insulation strips being suciently wide to engage said shield cylinder and space the two rst-mentioned cylinders therefrom and means for insulatingly attaching said deecting plates to said anode in 10 spaced relation from each other and from said shield cylinder.

13. A cathode ray storage tube comprising an evacuated envelope containing a grid cylinder, a cathode supported within said grid cylinder, a. first anode cylinder spaced from said grid cylinder, a second anode cylinder spaced from said first anode cylinder, all said cylinders being coaxial, electrostatic deflecting plates, a plurality of insulation strips extending axially of said cylinders and outside thereof, means for securing said insulation strips to said cylinders, a shield cylinder surroundingthe other cylinders and said plates, said insulation str-ips being suiiiciently Wide to engage said shield cylinder and space the three first-mentioned cylinders therefrom and means for insulatingly attaching said deflecting plates to said second anode in spaced relation from each other and from said shie1d cylinder.

RICHARD L. SNYDER, JR.

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

UNITED STATES PATENTS Number Name Date 2,213,174 Rose July 30, 1939 2,230,134 Solberg Jan. 28, 1941

Images