US2461667A

US2461667A - Electrical system

Info

Publication number: US2461667A
Application number: US700959A
Authority: US
Inventors: David E Sunstein
Original assignee: Philco Ford Corp
Current assignee: Space Systems Loral LLC
Priority date: 1946-10-03
Filing date: 1946-10-03
Publication date: 1949-02-15
Anticipated expiration: 1966-02-15

Description

Feb. 15, 1949. D. E. SUNSTEIN ELECTRICAL SYSTEM 2 Sheets-Sheet 1 Filed Oct. 3, 1946 L130 .PDO

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SUNSTE/N A T TOP/V5 VS Patented Feb. 15, 1949 ELECTRICAL SYSTEM David E. Sunstein, Cynwyd, Pa., assignor to Phllco Corporation, a corporation of Pennsylvania Application October 3, 1946, Serial No. 700,959

23 Claims. 1

My invention relates to electrical signalling, measuring and computing systems. More particularly, it provides a novel form of non-linear element to be used in such systems which may be altered at will.

Non-linear devices are in common use in most signalling, measuring and computing systems as modulators, demodulators, clippers and squarers. For each such use it is desired that there be a certain functional relationship between currents and voltages in the non-linear device, but it is usually not possible to adjust a non-linear device to fit a prescribed functional relationship, Instead it is customary to select a device which has a characteristic as close to the desired one as possible.

In my patent application, Serial No. 606,773, filed July 24, 1945, I have disclosed a means for obtaining a non-linear device whose characteristic is determined by the shape of an opaque mask interposed between the fluorescent screen of a cathode ray tube and a photoelectric cell.

The present invention embodies a conducting mask placed close to the screen of the cathode ray tube, thus dispensing with the photoelectric cell. The signal induced by capacitive association between the metal plate and the electron beam in the cathode ray tube is used to continue the deflection of the electron beam.

Thus my invention uses a cathode ray tube whose beam is caused to be deflected in one coordinate by the input signal. A conducting plate is cut to the shape of the non-linear characteristic desired, and is mounted close to the screen of the cathode ray tube.

The signal induced on the plate by capacitive action between the plate and the beam in the cathode ray tube is amplified and is fed to the second set of deflecting plates so that the electron beam follows the edge of the mask. Thus the signal on the second set of deflecting plates is related to the signal on the first set of deflecting plates by the functional relationship represented by the edge of the conducting plate. The conducting plate acts as a graph of output as a function of input, and this graph can be changed by changing the shape of the conducting plate.

Consequently an object of my invention is to provide a non-linear device whose characteristic can be changed at will.

Another purpose of my invention is to provide an improved non-linear device in which no photoelectric cell or light-shields need be, used.

Other objects of my invention, as well as some of the details of various forms of my invention will become apparent upon a study of the figures in which:

Figure 1 shows one form of my invention.

Figure 2 shows another form of my invention.

t Figure 3 shows a push-pull form of my invenion.

Figure 4 shows another modification of my invention.

In Figure 1 the cathode ray tube i is provided with an electron gun 2, an accelerator 3 and a control grid d as is customary in cathode ray tubes. These elements may be arranged to provide focusing control of the electron beam, or special focusing electrodes (not shown in the figure) may be incorporated in any of the ways which are currently used in the construction of cathode ray tubes. A high frequency signal is supplied to the grid by the beam modulation generator 5, which may conveniently be a vacuum tube oscillator. This signal causes the electron beam 6 to be modulated in intensity at the frequency of the beam modulation generator. In normal operation, the spot 7 at which the electron beam 6 impinges upon the screen 8 of the cathode ray tube will be at the edge of the conducting plate 9. This plate will then receive a signal by capacitive coupling from the beam at the frequency of the beam modulation. This Sig... nal is amplified in amplifier 50 and rectified in rectifier H to produce a direct voltage whose value is proportional to the strength of the signal input to the amplifier. This direct voltage is used as the deflecting voltage for the electron beam through the action of vertical deflecting plates l 2.

In order to understand the action of this feedback device in keeping the spot i at the edge of plate 9, consider that a disturbance should deflect the electron beam upwards, Then less signal would be picked up by the plate 9, and so less deflecting voltage would be delivered to the plates 52. This would cause the beam to be deflected downwards, and so would return the beam to the edge of the plate. Likewise, a disturbance which would tend to deflect the beam downward from the edge of the plate would send a greater signal through the system resulting in an upwards deflection. A stable spot is thus reached at the edge of the plate.

The input to the device is impressed upon deflecting plates l3, and thus deflects the beam horizontally. The feedback system maintains the posit-ion of the spot I at the edge of the plate 9, so that the voltage impressed on deflecting plates I2 by the rectifier H is related to the input by whatever function has been cut in the shape of use the voltage on deflecting plates I2 as my output. Accordingly I secure an output voltage related to the input voltage by the characteristic which is graphically represented by the upper edge of plate 9.

When my invention is used as a part of a measuring or computing device, it is used to obtain a functional relationship between two variables which may be indicated by Em and Emit. This functional relationship may be expressed in mathematical terms by the equation fEout=f(Ein) in which the symbol f(Em) represents a functional relationship. Specific functional relationships which might be used are Emit (Em) (square relationship) Eout=3V Em (cube root relationship) Eout=10g (Em) (logarithmic relationship) Eout=tan (Em) (tangent relationship) This list could be continued indefinitely since the supply of mathematical functions is inexhaustible if all the variations and combinations are included.

When my invention is used as a modulator or mixer, both signals may be applied to the input, or horizontal deflection plates I3. If the difference frequency is desired, a square law operation is preferable, so that the function f is chosen as a square relationship. As a linear, double sideband modulator, the carrier signal is preferably small in amplitude compared to the modulation signal. Against a square relationship for the function is desirable.

In use, after the desired function is chosen, a graph of the function is drawn to an appropriate scale in such a manner that Em is plotted in a horizontal direction and Eout is plotted in a vertical direction. The plate 9 in Figure 1 is then cut so that its upper edge conforms to the curve so plotted. Then the voltage corresponding to the variable Em is introduced into the input of my invention, and by the action of my invention there is obtained on the output a voltage proportional to the other variable Emit- When my device is in actual operation there will be only one value of Em present at any one instant, and there will be present simultaneously the proper value of EOllt as controlled by my invention, including the specific shape of the plate 9. At a succeeding instant, .however, a different value of Em will probably be present, so that Em varies with time. For proper operation, the output Emir must be able to keep up with the changes in Em. This may be accomplished by proper design of the amplifier section I and the rectifier section I I, according to principles well known to the designers of electronic equipment. Briefly, the requirement is that the band width of the feedback circuit shallbe large. If proper measures are taken to retain the spot I always on the top of the plate 9, I have found that this plate may be reduced to a thin wire having the shape of the top of plate 9.

It is to be observed that the intensity modulation of the beam caused by the beam modulation generator acts as a carrier frequency within my invention, but that this frequency does not appear in the output circuit. This carrier frequency is preferably chosen with respect to the time constant of the filter in the rectifier II so that the carrier frequency is eliminated by this filter. One

method of doing this is to choose the carrier frequency to be considerably higher than the cut-off frequency of this filter.

In the form of my invention which I have just described, means are employed in the design of I2, beam 6, spot I and plate 9. If this closed loop circuit is designed to be self-oscillatory, the beam modulation generator 5 may be eliminated, the rectifier I I may be placed external to this loop, and the plate 9 may be replaced by a stiff wire I4, as is shown in Figure 2. In this embodiment of the invention, the strength of oscillation of the feedback circuit is controlled by the capacitive association between the wire and the electron beam, which now oscillates along a vertical path between wire I4 and point Ma so that the end of the electron beam spreads out into a line Ia. This selfgenerated oscillation acts as a carrier frequency in the operation of the feedback system, and should be high for the same reasons that the frequency supplied by the beam modulation generator 5 is preferably high.

In this form of my invention, since the voltage on the deflecting plates I2 is a modulated carrier, a demodulator or rectifier system I5 is used to obtain the output signal,

When this embodiment of my invention is used in a measuring or computing device, the input variable Em is impressed upon the input terminals, and the voltage appearing on the output tenninals is proportional to the desired output variable Eollt. The relationship between these two variables is now controlled by the shape of wire I4, which is formed to conform to the aforementioned graph of the functional relationship between Em and Eout.

At any one instant, Em has a specific value which positions the beam 6 to a specific horizontal position. In the vertical direction the beam oscillates by virtue of the closed feedback loop comprising wire I4, amplifier III, deflecting plates I2 and beam 6. The amplitude of oscillation is such that the beam oscillates between the position of the wire I4 and a symmetrically disposed position I IA beneath the wire. The locus of all such symmetrically disposed positions is represented by the line MB in Figure 2. Since this amplitude of oscillation is caused by the voltage on plates I2, this voltage is rectified and filtered by rectifier I 5 to give a direct voltage Whose value is proportional to the oscillation of the beam and thus is proportional to the vertical position of the wire I4. Since this wire is positioned according to the desired function, the output is related to the input by the desired functional relationship.

At each successive instant, the value of Em will probably be different than it was at each preceding instant. Thus Em is usually a function of time, and my invention must re-act quickly enough to assure that the output is properly related to the input. This requires the same conditions in the rectifier I5 and in the oscillation frequency of the beam and band width of feedback path as were discussed in connection with the first embodiment of my invention. Thus the time constant of the rectifier filter must be low enough and the frequency of beam oscillation and band width of feedback amplifier must be high enough.

The circuit connections which I have outlined with the aid of Figure 2 will also operate with the wire replaced by the plate 9 of Figure 1. In

which their difference is taken by the voltage subtractor l8. This difference voltage is used as the deflecting voltage for the deflecting plates [2. The use of two plates tends to make the position of equilibrium of the spot on the fluorescent screen more precisely placed. This follows from the fact that if the spot is just above the gap [9, between the plates l6 and 11, a full strength downward deflection voltage is supplied to plates l2, whereas if the spot is just below the gap, a full strength upward deflection voltage is supplied to plates i2.

In a further variation of my invention the edge of the plate 9 is replaced by the system shown in Figure 4. Here a plate 20 acts as the signal pick-up plate, and a shielding plate 2! acts to screen the lower part of plate 20 from the electron beam. Equili-brium of the beam is obtained near the edge of shield 2|, so the shape of this shield will determine the functional characteristic of the device.

This variation shown in Figure 4, is also adaptable to the following of the motion of an object. Thus, if shield 2| is moved vertically, the spot will follow the motion, so the output of the device will be an electrical replica of the motion of the shield 2f. In this application, the fact that the shield 2i is grounded facilitates the design of the equipment.

The above specification described detailed descriptions of certain forms of my invention, but I wish my invention to be delineated by the following claims.

I claim:

A non-linear circuit arrangement comprising a cathode ray tube having a source for generating an electron beam, a screen mounted within a transparent dielectric, a conducting mask in electrical proximity to the screen of said cathode ray tube and in capacitative coupling with said beam, said mask having a predetermined construction in accordance with the desired non-linear operation and circuit connections from said mask to said cathode ray tube.

2. In a modulating system, a cathode ray tube having means for generating an electron stream, a conducting plate having a predetermined shape capacitatively coupled to said electron stream, means for applying input signals to said cathode ray tube, and means including said plate for generating signals related to said input signals in. accordance with the shape of said plate.

3. A non-linear circuit arrangement comprising a cathode ray tube having means for generating an electron stream, a pair of deflecting means, means for applying an input signal to one of said deflecting means for deflecting said cathode ray in one coordinate in accordance with said signal input, a conducting plate in electrical proximity to said electron stream, circuit connections from said plate to the other of said deflecting means for deflecting said beam in another coordinate in accordance with the construction of said plate so that the signal in said other deflecting means is related to the input signal on said deflecting means by the functional relationship of the construction of said conducting plate.

aeeaeev 4. A non-linear circuit arrangement comprising a cathode ray tube having a pair of deflecting means and, a cathode ray emitter, means for applying an input signal to one of said deflecting means for deflecting said cathode ray in. one coordinate, a plate having a predetermined construction, said plate being in electrical relation to the electron stream produced by said ray emitter, and means including said plate for applying a signal to the other of said deflecting means, said last mentioned signal being related to the signal on said one of said deflecting means in accordance with the construction of said plate.

5. A non-linear circuit arrangement comprising a cathode ray tube having a pair of deflecting means and a cathode ray emitter, means for applying an input signal to one of said deflecting means for deflecting said cathode ray in one coordinate, a plate having a predetermined construction, said plate being in electrical rela- 'tion to said cathode ray tube, and means including said plate for applying a signal to the other of said deflecting means, the shape of said plate being a graph of the desired output as a function of the input so that said last mentioned signal is related to the signal on said one of said deflecting means in accordance with the construction of said plate.

6. In combination, a cathode ray tube having a screen, an intensity control electrode, a pair of deflecting means and an electron ray emitter, a source of high frequency signals, means for applying said signals to said electrode for modu lating the intensity of said electron ray, means for applying a signal input to one of said deflecting means, a conducting plate capacitatively coupled to said cathode ray tube for receiving signals by capacitative coupling therefrom, means for rectifying said received signals to produce a direct voltage dependent upon the strength of the signal on said plate and means for applying said direct voltage to the other of said pair of deflecting means.

7. In combination, a cathode ray tube having a screen, an intensity control electrode, a pair of deflecting means and an electron ray emitter, a source of high frequency signals, means for applying said signals to said electrode for modulating the intensity of said electron ray, means for applying a signal input to one of said deflecting means, a conducting plate capacitatively I coupled to said cathode ray tube for securing signals by capacitative coupling from the electron stream produced by said electron emitter, and a feed-back circuit from said plate to the other of said deflecting means.

-8. In combination, a cathode ray tube having an intensity control electrode, a pair of defleeting means and an electron ray emitter, a source of high frequency signals, means for applying said signals to said electrode for modulating the intensity of said electron ray, means for applying a signal input to one of said deflecting means, a conducting plate capacitatively coupled to the electron stream produced by said electron emitter for securing signals by capacitative coupling thereto, and a feed-back circuit from said plate to the other of said deflecting means for maintaining the position of said electron ray in a predetermined relation with respect to said plate.

9. In combination, a cathode ray tube having a pair of deflecting means and an electron ray emitter, and a conducting plate having a predetermined shape, capacitatively coupled to the electron stream produced by said emitter.

10. In combination, a cathode ray tube having a pair of deflecting means and an electron ray emitter, and a conducting plate having a predetermined shape, capacitatively coupled to the electron stream produced by said emitter, said conducting plate being external of said tube and electrically connected thereto.

11. In a modulating system, a cathode ray tube having an electron stream, a conducting plate having a predetermined shape capacitatively coupled to said electron stream, means for applying input signals to said cathode ray tube, and means including said plate for generating signals related to said input signals in accordance with the shape of said plate, said plate being replaceable by other plates of varying shapes in accordance with the desired modulations of said input signals.

12. In a modulating system, a cathode ray tube having an electron ray emitter, a set of deflecting means, a conducting plate capacitatively coupled to the stream generated by said emitter, means for applying an input signal to one of said deflecting means, and means including electrical connections from said conducting plate to the other of said deflecting means for generating signals related to said input signals in accordance with the shape of said plate.

13. In a modulating system, a cathode ray tube having an electron ray emitter, a set of deflecting means, a conducting plate of a predetermined shape capacitatively coupled to said cathode ray tube, means for applying an input signal to one of said deflecting means, a feed-back circuit including circuit connections from said plate to the other of said deflecting means for maintainin the ray on the edge of said plate so that the signal impressed on said other defleeting means is related to the input by whatever functions has been cut in the shape of the edge of said plate.

14. In a modulating system, a cathode ray tube having an electron ray emitter, a set of deflecting means, a conducting plate, the edge of which is a curve of a predetermined function capacitatively coupled to the electron stream generated by said emitter, means for applying an input signal to one of said deflecting means, a feedback oscillator circuit including circuit connections from said plate to the other of said deflecting means for maintaining the rayon the edge of said plate so that the signal impressed on said other of said deflecting means is related to the input by whatever function has been cut in the shape of the edge of said plate.

15. In a modulating system, a cathoderay tube having an electron ray emitter, a set of deflecting means, a conducting wire of a predetermined shape capacitatively coupled to the electron stream generated by said emitter, means for applying an input signal to one of said deflecting means, a feed-back oscillator c rcuit including circuit connections from said wire to the other of said deflecting means for maintaining a condition of oscillation of amplitude dependent upon the location of said wire.

16. In combination, a cathode ray tube having a screen and an electron emitter, a pair of plates having their edges of predetermined shape and spaced from each other, said plates being capacltatively coupled to the electron stream generated by said emitter, a circuit connection for each of said plates, said circuits being in pushpull relations, means for applying input signals to said cathode ray tube and means controlled by said push-pull circuits for controlling the deflection of said cathode ray.

1'1. In an electrical circuit, a cathode ray tube having a screen and a source for generating a beam impinged on said screen, an input ;'signal for deflecting said beam in one coordinate, a conducting plate cut to the shape of a non-linear characteristic desired, mounted close to said screen in capacitative relation to the electron beam, an amplifier circuit connected to said plate, the signal induced on said plate by the capacitative action between said plate and beam deflecting said beam in the other coordinate for maintaining the beam along the edge of said plate.

19. In an electrical circuit, a cathode ray tube having a screen and a source for generating a beam impinged on said screen, an input signal for deflecting said beam in one coordinate, a conducting plate cut to the shape of a non-linear characteristic desired, and acting as a graph of output as a function of input, mounted close to said screen in capacitative relation to the electron beam, an amplifier circuit connected to said plate, the signal induced on said plate by the capacitative action between said plate and beam deflecting said beam in the other coordinate for maintaining the beam along the edge of said plate.

19. In an electrical circuit, a cathode ray tube having a screen, a source for generating a beam impinged on said screen, a first set of deflectors for deflecting said beam in one coordinate, a

second set of deflectors for deflecting said beam in the other coordinate, a grid, a source of high frequency connected to said grid for modulating said beam in intensity at the frequency of said high frequency source, an input signal source connected to said first deflectors for deflecting said beam along one coordinate, a conducting plate adjacent said screen for receiving signals by capacitative coupling from the beam at the frequency of the beam modulation, said plate bearing an edge shaped in accordance with a desired function of said input signal, an amplifier connected to said plate, a rectifier connected to the output of said amplifier, the output of said rectifier being a direct voltage whose value is proportional to the strength of the signal input, circuit connections from said rectifier to said second set of deflectors for deflecting said beam along the other coordinate to maintain the beam on the edge of said plate, the voltage applied to said second set of deflectors being related to the input signals by whatever function has been cut in the shape of the upper edge of said plate.

20. In an electrical circuit, a cathode ray tube having a screen, a source for generating a beam impinged on said screen, a first set of deflectors for deflecting said beam in one co ordinate, a second set of deflectors for deflecting said beam in the other coordinate. a grid, a source of high frequency connected to said grid for modulating said beam in intensity at the frequency of said high frequency source, an input signal source connected to said first deflectors for deflecting said beam along one coordinate, a conducting plate adjacent said screen for receiving signals by capacitative coupling from the beam at the frequency of the beam modulation,

an amplifier connected to said plate, the output of said amplifier being a voltage whose value is proportional to the strength of the signal input, circuit connections from said amplifier to said second set of deflectors for deflecting said beam along the other coordinate to maintain the beam on the edge of said plate, the voltage applied to said second set of deflectors being related to the input signals by whatever function has been cut in the shape of the upper edge of said plate, and an output circuit connected to the output of said amplifier.

21. In an electrical circuit, a cathode ray tube having a screen, a source for generating a beam impinged on said scieen, a first set of deflectors for deflecting said beam in one coordinate, a second set of deflectors for deflecting said beam in the other coordinate, a grid, a source of high frequency connected to said grid for modulating said beam in intensity at the frequency of said high frequency source, an input signal source connected to said first deflectors for deflecting said beam along one coordinate, a conducting plate adjacent said screen for receiving signals by capacitative coupling from the beam at the frequency of the beam modulation, said plate having an edge conforming to a curve whose one coordinate is in accordance with said input signal and whose other coordinate is in accordance with said output sig-- nal, an amplifier connected to said plate, a rec tifler connected to the output of said amplifier, the output of said rectifier being a direct voltage whose value is proportional to the strength of the signal input, circuit connections from said rectifier to said second set of deflectors for deflecting said beam along the other coordinate to maintain the beam on the edge of said plate, the voltage applied to said second set of deflectors being related to the input signals by whatever function has been out in the shape of the upper edge of said plate.

22. In an electrical circuit, a cathode ray tube having a screen and a source for generating a beam impinged on said screen, an input signal for deflecting said beam in one coordinate, a conducting plate cut to the shape of a non-linear characteristic desired, mounted close to said screen in capacitative relation to the electron beam, a solid dielectric disposed between said screen and conducting plate, an amplifier circuit connected to said plate, the signal induced on said plate by the capacitative action between said plate and beam deflecting said beam in the other coordinate for maintaining the beam along the edge of said plate.

23. In an electrical circuit, a cathode ray tube having a screen, a source for generating a beam impinged on said screen, afirst set of deflectors for deflecting said beam in one coordinate, a sec ond set of deflectors for deflecting said beam in the other coordinate, a grid, a source of high frequency connected to said grid for modulating said beam in intensity at the frequency of said high frequency source, said elements being enclosed in a glass envelope, an input signal source connected to said first deflectors for deflecting said beam along one coordinate, a conducting plate outside said envelope adjacent said screen for receiving signals by capacitative coupling from the beam at the frequency of the beam modulation, said plate bearing an edge shaped in accordance with a desired function of said input signal, an amplifier connected to said plate, a rectifier connectedto the output of said amplifier, the output of said rectifier being a direct voltage whose value is proportional to the strength of the signal input, circuit connections from said rectifier to said second set of deflectors for deflecting said beam along the other coordinate to maintain the beam on the edge of said plate, the voltage applied to said second set of deflectors being related to the input signals by whatever function has been cut in the shape of the upper edge of said plate.

DAVID E. SUNSTEIN.

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

UNITED STATES PATENTS Number Name Date 2,171,150 Shelby Aug. 29, 1939 2,189,898 Hartley Feb. 13, 1940 2,256,336 Beatty Sept. 16, 1941 2,262,406 Rath NOV. 11, 1941 2,307,438 Whittaker Jan. 5, 1943 2,357,922 Ziebolt et al. Sept. 12, 1944