US2624021A

US2624021A - Beam type electron discharge device

Info

Publication number: US2624021A
Application number: US156660A
Authority: US
Inventors: Bernard C Gardner
Original assignee: Raytheon Manufacturing Co
Current assignee: Raytheon Co
Priority date: 1950-04-18
Filing date: 1950-04-18
Publication date: 1952-12-30
Anticipated expiration: 1969-12-30

Description

Dec. 30, 1952 B, C, GARDNER 2,624,021

BEAM TYPE ELECTRON DISCHARGE DEVICE Filed April 18, 195o Patented Dec. 30, :1952

UNITED STATES PATENT OFFICE.`

BEAM TYPE ELECTRON DISCHARGE DEVICE Bernard C. Gardner, Redwood City, Calif., as-

signor to Raytheon Manufacturing Company, Newton, Mass., a corporation of Delaware Application April 18, 1950, Serial No. 156,660

(Cl. S13-72) 9Claims.

This invention relates to electron discharge devices, and more particularly to an amplifier of the deflection modulation type which may be used as an analogue computer. y f

Cathode ray tubes can be used as analogue computers by placing a target in the path of the electron stream and masking said target with the shield having a particular configuration such that the beam impinges partially on the mask and partially on the target electrode. By then deflecting the beam, the number of electrons striking the target electrode may be varied in accordance with any desiredV function of the input deflection voltage by the use of a particular contour'of masking electrode. For example, a beam may be emitted from a cathode ray tube gun in the form of a triangular plane with the apex of the plane at the gun' and the base of the plane a vertical line of impingement of electrons on the target or masking electrodes. If the electron beam is then moved horizontally such that the position of the line of impingement of the beam on the masking electrode changes, the contour of the edge of the masking electrode will determine the number of electrons striking the target electrode.

It has been found that certain inaccuracies are inherent in this device since the ends of the line of impingement of the beam would not have a density which is uniform with respect to the density of the impingement line at the y center thereof. Therefore, it becomes impossible to compute exactly the shape of the curve vof the masking electrode. Since the accuracy 55.-,

of the device depends upon the accuracy to which the curve of the masking electrode is computed, and, since adjustment of this curve is impossible following assembly of the device, it has been found to be impossible to construct this l type of computer with large degrees of accuracy.

This invention discloses a beam deflection device wherein the edge effects of the beam are eliminated, and hence the curve of the masking electrode may be computed with a high degree of accuracy.

Briefly, the invention embodies the use of an electron beam in the form of a disk, the electrons of said beam emanating from a cathode at the center of said disk. The periphery of said disk impinges upon an apertured, cylindrical masking electrode behind which is positioned a target or collecting electrode. Disk-shaped deflection plates are positioned substantially parallel to the electron beam disk such that the voltages applied between the deflection plates cause the disk to be deformed into a conical beam so that either more or less electrons impinge upon the masking electrode, the number of electrons impinging upon the masking electrode being controlled by the size and shape of apertures therein.

In addition, since the total current of the bean is limited by the area of impingement of the electrons on the anode structure and the resultant heating thereof, the radial or disk type beam allows a much higher current than a linear type beam with the resultant higher signal level. Also, the radial type device disclosed herein may be made considerably more compact than a linear type device, being, for example, two or three inches in diameter and two or three inches in length as against a similar diameter and ten Eo twelve inches in length for a linear type strucure.

Other and further advantages of this invention will become more apparent as the descrip- .tion thereof progresses, reference being had to the accompanying drawing, wherein:

Fig. 1 illustrates a longitudinal, cross-sectional view of an electron discharge device embodying this invention taken along line I-I of Fig. 2;

Fig. 2 illustrates a transverse, cross-sectional vview of the device shown in Fig. 1 taken along line 2-2 of Fig. 1; and

Fig. 3 illustrates a circuit utilizing the device of Figs. 1 and 2. Referring now to Figs. 1 and 2, thereis shown ran evacuated envelope I0 which may be made,

for example, of glass having positioned therein -a cathode II coaxial withy envelope Ill. Cathode II comprises a cathode cylinder I2 which may be of any' desired conductive material such as, for example, tungsten. Inside cylinder I2 is a heating element comprising a coil I3, one end of which is attached to the cylinder I2 and the other end of which extends down through the bottom end of cylinder I2 and is connected to a lead-in member Id which. passes through a glass seal in the base of envelope I0. The cathcae cylinder I2 is supported by a similar leadin member I5 which passes through a glass seal inthe base of envelope II). :A portion of the outer surface of cylinder I2 is coated with electron emissive material Il such that, when a suitable heater voltage is applied between leads .I4 and I5, cylinder I2 will be raised to a sufficient temperature for coating I1 to emit electrons.

Surrounding the portion of cylinder I2 which 1s coated with electron emiss'ive material and coaxial therewith is a masking electrode I3 which is cylindrical in form and has a plurality of apertures therein. Masking electrode Ill is supported by a plurality of lead-in members IS which pass through the bottom of envelope I and are sealed therein. Surrounding masking electrode I8 and coaxial therewith is a collecting electrode 23 Which is cylindrical in form and is supported by a plurality of lead-in members 2v! which are sealed through the bottom of envelope IQ.

Positioned above cathode II is a metallic disk 22 which is supported by a lead-in member 23 sealed through the top of envelope Ill. Disk 22 operates as a deflection plate and is positioned slightly above the upper end of masking Aelectrode I8 and is somewhat smaller in diameter than masking electrode I8. Positioned below masking electrode I3 is a second deflection plate 24 which comprises a liat, annular metallic member supported by lead-in members 25 sealed through Ythe bottom of envelope Ill. Member 24 has an outside diameter which is equal to the diameter of member '22 and has a hole 2B in the center thereof to allow 4the passage of the cathode I I therethrough.

Referring now to Fig. 3, there is illustrated a mode of operation of the device of Figs. 1 and 2. The heater coil I3 has a voltage applied thereacross by means of a battery 21. Cathode II is attached to a variable tap 28 of a battery 29 which may have a total overall value of, for example, a few hundred volts. The negative end of battery 29 is connected through input load resistors 3Q and 3l to lower and

upper deection plates

24 and 22, respectively. An input signal amplifier has its output connected across electrodes 22 and 2li, whereby a signal .is impressed therebetween. Masking electrode iii is connected to .a tap 32 on battery 23 which is considerably more positive than variable tap 28. Collecting electrode 2t is connected through an output load resistor 33 through the positive end of battery 29. rlhe electron beam is attracted to masking electrode I8 and collecting electrode 2l! due to the positive potentials between the cathode I I and said electrodes. By adjustment of variable tap 28, the negative bias on the deflection electrodes 2li Vand 22 may be adjusted such that the point of impingement of the electron beam on 4the masking electrode I8 is a sharp, Ycircular line. If desired, other electrodes may be used in the structure to facilitate focusing 'and .to control the intensity of the electron beam.

When a voltage is applied between

Yelectrodes

22 and 24 by a signal from a signal input arn- .plier 34, the beam will be moved either up or down at the point of impingement of said beam on masking electrode I 8 dependent on vthe instantaneous polarity of the input signal. lDue .to the non-uniform shape of the apertures in the masking electrode I8, movement of the point of impingement of said beam on masking electrode vI8 varies the current which passes through said apertures to the collecting electrode 2B, thereby varying the voltage developed across load resistor 33. The voltage developed across resistor 33 is fed to an output signal amplifier to be used for any desired purpose. By varying the shape of the apertures in masking elect-rode I 8, .the output signal developed across resistor 33 may be made to have any desired functional relationship to the input signal applied to

plates

22 and 24. In effect, the output signal represents the solution of a particular problem according Cil 4 to a particular formula and, therefore, the system may be termed an analogue computer.

If desired, the output electrode may be made in a plurality of sections, each section covering one or a plurality of apertures in the masking electrode I3. Each output section may be fed to a different output, and the apertures in front of the various output sections may `have different shapes, whereby a plurality of different functions may be computed simultaneously. Due to the fact that the beam is radial, it has no end points in .a direction perpendicular to the deiiecting direction, and hence the inaccuracies which are encountered in linear beams are eliminated.

This completes the description of the particular embodiment of the invention illustrated herein. However, many modifications thereof will Vbe apparent to persons skilled in the art. For example, the signal could be taken from the masking electrode rather than the collecting electrode, if desired. Other types of cathodes could be used, and any desired shape or size of aperture could be used in the masking electrode I8 Without departing from the spirit and scope of this invention. Therefore, applicant does not wish to be limited to the particular `details of the embodiment of the invention illustrated herein, except as defined by the'appended claims` What is claimed is:

1. An electron discharge device comprising an electron source, means for forming electrons from said source into a conical beam, a target electrode, and means for varying the conical angle of said beam prior to impingement of said beam on said target electrode to thereby vary the number of electrons impinging on said target electrode, the percentage rof said beam which impinges on said target electrode varying as a continuous function of said conical angle.

2. An electron discharge device comprising .an electron source, means for forming electrons from said source into a conical beam, Va masking electrode having non-linear discontinuities therein upon which a portion of said beam will impinge, a collecting electrode, and means for varying the conical angle of said beam prior to impingement of ysaid beam .on said masking electrode to thereby Vary .the number of relectrons Iimpinging on :said Vmasking electrode.

.3. An electron discharge device comprising an electron source, means for forming electrons from said sourceinto a conical beam, a masking electrode rhavingan aperture therein, said aperture .having a non-linear contour, a collecting electrode positioned outside said masking yelectrode, and means for varying the conical angle of said beam prior to impingement of said beam on said masking electrode.

4. An electron discharge device comprising-an electron source, means for forming electrons from said source into a conical beam,a masking electrode upon which a portion of said beam will impinge comprising an apertured cylinder surrounding said source, a collecting electrode positioned outside said masking electrode Acoaxial with said source, the apertures of said cylinder having sides which are non-linear in a direction parallel to the axis of said beam, and means for varying the conical angle of said beam prior to impingement of said beam on said masking electrode.

5. A computer comprising an electron discharge device Yhaving signal input means and signal output means for producing a vsignal output bearing a non-linear continuous functional relation to a signal supplied to said input means, said discharge device comprising an electron source, means for forming electrons from said source into a conical beam, a target electrode which is non-uniform with respect to said beam, and means prior to said impingement of said beam on said target electrode for varying the conical angle of said beam.

6. A computer` comprising an electron discharge device having signal input means and signal output means for producing a signal output bearing a non-linear continuous functional relation to a signal supplied to said input means, said discharge device comprising an electron source, means for forming electrons from said source into a conical beam, a masking electrode upon which a portion of said beam will impnge, a collecting electrode positioned outside said masking electrode, and means prior to the impingement of said beam on said masking electrode for deflecting said beam substantially transversely to the direction of motion of said beam.

7. An electron discharge device comprising a source of electrons adapted to produce a conical electron beam, an electrode positioned in the path of said beam', said electrode having a discontinuity therein which varies as a continuous function of the conical angle of said beam, and

a beam deflection element intermediate said source and said electrode to vary the conical angle of said beam.

8. An electron discharge device comprising a source of electrons adapted to produce a conical electron beam, an electrode positioned in the path of said beam, said electrode having an aperture therein which varies as a continuous function of the conical angle of said beam, and a beam deiiection element intermediate said source and said electrode adapted to vary the conical angle of said beam.

9. An electron discharge device comprising a source of electrons adapted to produce a conical electron beam, an electrode positioned in the path of said beam, said electrode having a discontinuity therein which varies as a continuous function of the conical angle of said beam, a beam deflection element intermediate said source and said electrode adapted to vary the conical angle of said beam, and a target positioned in the path of said beamk on the opposite side of said electrode from said source.

BERNARD C. GARDNER.

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

UNITED STATES PATENTS Number Name Date 2,164,922 Hollmann July 4, 1939 2,176,589 Hollmann Oct. 17, 1939 2.205.500 Strutt et al. June 25. 1940