US2937313A - Signal storage tube - Google Patents

Description

May 17, 1960 Y J. E. OTTO 2,937,313- SIGNAL STORAGE TUBE Filed March IfO, 1959 2 Sheets-Sheet x Fig. I

Invenfar:

Jm/u'm E. Oilo y 1960 J. E. OTTO SIGNAL STORAGE TUBE Filed March 30, 1959 2 Sheets-Sheet 2 In venfor:

J c/u'm E 0210 2931313 SIGNAL STORAGE TUBE Joachim E. Otto, Ulm (Danube), Gerinany, assignor to The present invention 7 relates to storing ofelectrical United. States signals and, more particularly, to a signal storage-tube 1 having a substantially strip-shaped targetelectrode ,and

oneor two electron guns used for producing both= writing and reading beams.

In the following discussiomeachtype; of signal storing while each kind of signal target electrode. r 1 s The necessity of storing-electrical-signals fora limited period of time arises, for examplegif the video frequency signal band in a radar? set has first to be.com pressed prior to its transmission, for the purposenof transmission by means having aba'nd width which is narrower than ,saidjsignal band. -Signal storage tube are particularly suitable for this purpose. 1

In storage tubes for this andjother similar purposes, wherein signals are recorded on target electrodes, it is usual practice-to causean-electron beam which has been intensity-modulated by the signal voltage to travel once or several times over said target electrode using suitable deflection means, whereby changes in the electrical charges on said target electrode are stored, said changes being dependent on 'the'instantaneous-intensities of the respective beam-modulating signals. The; methods of producing such changes are well known. With known.

storing electrode is called a cathode ray ,tube is briefly calleda storage tube]? :1?

storage tubes, the intensity modulation of the electron beamis obtained by means of cathode control or Wehnelt electrode control. t v

In said storage tubes, both the pick-up and the oblitera' tion of the stored'sig'nals are likewise'obtained by means of an electron-beam which, however, has a constant-intensity and which iscaused to'travel with the aid of de flecting means at suitable-velocity once over the same track onthe target electrode along which'the first elec- .tron beam travelled'when writing the respective signals, whereby signal voltage variationsare obtained in aworking resistance insertedin the circuit of a signal collecting plate on the side ofTthe targetnelectrode facing away 'from the electron gun. Intheiramplitude distribution,

the above-mentioned voltage variations follow the stored charge distribution on the track of the target electrode and, in this way, they represent the'signals stored thereon.

When using the above type of=storage tube, there ap-v pears the disadvantage that, due to' the. nonlinearity of the beam current characteristic of the Wehnelt electrode potential, the relationship between the control voltage and the beam current is also nonlinear, whereby the amplitude of the .signals to be transmitted is distorted; In addition, it is, often necessaryin lithe operation of such storage tubes that a directcurrent component be super- I imposed to the-alternating-current' component of the beam current'including the, signal; Due to the nonlinear shape of-the curve'characteristic, an optimum ad.-

justment of the operating characteristic ofzgthe storage .tube is not readily possible in case of high amplitude als Moreover, the output signal compressedbandwidth in this type of storage tube also contains, even in the absence of input signals, the compressed noise spectrum of all of the preceding stages of the apparatus.

Furthermore, it should be borne in mind that the range of information which can be stored ,is rather "small.

With other embodiments of storage tubes which are suitable for the above-mentioned purpose, the changes in either the electrical charges or in the electrical properties of the target electrode are obtained by. applying the signal voltage to a collector electrode or to a gridlike electrode, disposed immediately before or directly .on the target electrode, or by applying said signal voltage to the ,target electrode itself in cooperation withan electron beam of constantintensity which is caused to' travel once or several times overv said target electrode by suitable deflecting means. The methods causing 'said changes in the target electrode of such tubes are likewise. known per se. With said storage, tubes, thepickup'iand, if required, .also the obliteration of the stored signals are done by means of an electron beam having a constant intensity, which electron beam is also swept by deflecting means once at a suitable velocity over the same track on the target electrode over which the first t electron beam was swept when writing the'respective .rUsing this type of storage tube, it-"has, likewise, been found "disadvantageous that the output signal' of compressed band width, even in the absence of input'si'gnals',

always contains the compressed noise spectrum of the] preceding stages. In addition, it should be taken into consilderation that the range of information is also smal Embodiments of the two forenientioned' groups of storage tubes have been known, in which the electron: beam-or beams have a circular or rectangular cross section. Furthermore, cathode ray tubes have been known having anelectronbeam of circular cross see tion. In-these tubes, the electron beam issubjected to adeflectionwhich is dependent on the amplitudeof the signal voltage fed to-the-tube, asfin oscillog'raph: tubes.

' 'It' is 'an object of the present invention to provide a? storage tubein which the'aforementioned disadvantages are overcome bya suitable 'design of the electron beam and by means of a dilferent control system. In the following, the deflection ofthe electron beam, dependent on the signal voltage, will be explained as being distinguished from the cyclical electron beam sweep. 7

It is another object of the invention to provide a' storage tube in which the electron beam 'isidesigned as a band-shaped electron beam having a cross-sectional ratio of at least 1:5, so that the longercrossksectional dimensions of the electron beams are oriented perpen dicularly to the longitudinal extensionof; the target electrode over which the electron beams travel; Means'a re provided by which the "writing beam, depending on the signal to be stored, is deflected in thedirection of the longer cross-sectional dimension .of the, electron beam;

and the band-shaped beams have a=constantmean intensity for one deflecting operation whether a writing cycle or reading cycle. 'T 1;; 7 -Still further objects and the entire scope of applicability of the present invention will become apparent from V 5 the detailed description given hereinafter; it should be understood, however, that the detailed description v and those skilled in the art from this detailed description.

In the drawings:

Figure 1 is a fragmentary schematic showing of a band-shaped beam impinging on a target electrode, and

Figure 2 is a partial perspective view showing a storage tube electrode arrangement according to the invention.

Referring in detail to the drawings, Figure l schematically shows a portion of an elongated target electrode on which two tracks 3 and 4 adjacent one another are provided side by side and a signal collecting plate 5 is arranged on the side ofthe target electrode opposite the electron-emitting source, in the circuit of which a load resistance '6 is inserted. -Al'so forming a part of the circuit is an electron beam 1-haVingan approximately rec'- 't-angular cross section, said beam being caused to travel a pair of beam deflection electrodes 2 to modulate the position of the beam on the target. To avoid crowding of the drawing, the conventional collector electrodejs omitted. As long as no signal voltage is applied to the deflecting plates 2, the electron beam 1 will travel along the track '3, but .when a signal voltage is applied to the deflecting plates 2, the electron beam 1, while being swept over the target electrode in the direction of the arrow, will be deflected from the track 3 to the track 4, whereby the relative electrical state of charge of the two tracks 3 and 4 of the target electrode will be changed, said state of charge being indicated by shading in Figure 1.

, For pick-upjof the signals stored in the target electrode, there is used also an electron beam 1 having an approximately rectangular cross section, said beam being produced eitherby means of the same electron gun used for the signal writing electron beam, or by means of another electron gun, whereby said second beam (not shown) is swept over the target electrode at a suitable velocity by conventional deflecting means. The longer cross-sectional dimension of the electron beam picking up the stored signals should be designed such, that -it extends from the inner edge to at least the outer edge over the entire width of one track.

Figure l shows an arrangement having two similar tracks. If, with said arrangement, theelectron pick-up beam is caused to travelalong the track 3, the stored signal will be represented by the gaps on :said track, whereas, if the electron pick-up beam is swept along the track 4, the stored signals will be represented on said latter trackjby the spots charged by the deflected signalwriting electron beam. With the use of either of the two aforementioned systems, pick-up voltage variations will appear in the load resistance 6;, said variations corresponding to the stored signals, whereby the polarities of the voltage variations in the load resistance, however, are opposite in the two possibly different pick-up tracks. The two tracks 3 and 4 may be designed to be either similar to or different from one another.

Obviously, the track on the target electrode, from which no stored signals are to be taken up, need not have any storing action which means that it may be, for instance, a collector electrode.

Furthermoregit is evident that the track designed to be a collector electrode need not be in the plane of the track comprising the target "electrode. On the contrary, the track designed to be a collector electrode may be arranged so that it is shifted from the plane of the target track in the direction 'of the electron emitting source "as well as in the other direction.

In case of similar design of the two tracks, it "will be advantageous for various purposes, if either "track has its own signal collector plate electrically insulated from the signal plate of the other track, whereby a load resistance "can be inserted in the 'ci'riiuit at either signal plate. It, with the use of the abovementioned target electrode, the stored signals are picked up from the two tracks by means of an electron beam having a band-like cross section, the longer cross-sectional axis of which reaches at least over the entire width of the two tracks, tWlO paraphased output signal voltages will be available at the two load resistances.

In the above mentioned embodiments of target electrodes employed in the storage tubedesigned in accordance with this invention, the two tracks may be arranged with their long sides adjacent one another and spaced at a suitable distance, for the purpose of fully suppressing the noise level in the input signal of the storage tube or for the purpose of obtaining a threshold value.

It is evident that the above described embodiments of the storage tube according to this invention are not confined to arrangements with linear tracks, i.e., the tracks may'als o be circular.

Figure 2 schematically shows the essential components of the embodiment of a signal storage tube having an annular target electrode, the structure of which is principally the same as that of the target electrode shown in Figure 1. The rneans for obtaining a strip-like beam will be explained with reference to Figure 2.

An electron beam having a circular cross section is first produced by means of both a cathode 11 and a symmetrically designed Wehnelt cylinder 12, said electron beam being adapted to be focussed onto the tracks of the target electrode by means of symmetrically designed electrodes 13, 14,-1.5, representing an electron lens. The electron lens 13, 14, 15, has been designed as an electrostatic single lens. This electron lens may also be designed as an electrostatic accelerator lens or a magnetic lens. In the embodiment of Figure 2, the electron beam is circularly swept by means of a pair of deflecting coils (not shown), although electrostatic deflecting means may be employed. The swept electron beam, having a circular cross section,- is spread in a dir'ection radial with respect to the axis of the electron gun by "means of the annular electrostatic cylinder lens 16, 17, 18, which produces an annular cylindrical field, so that that the electron beam 10, when impinging on the target elect-rode 24, has an approximately rectangular Cross section. In the embodiment of Figure 2, the ann'ula'r cylinder is designed as an electrostatic single lens. An annular electrostatic accelerator lens may, likewise, be used, said lens producing an annular-cylindrical field. The electron beam, which is spread apart by annular deflection means comprising two rings 19 and 20, is also radially deflected in accordance with the signal to be stored. The target electrode maybe designed as shown in "Figure l, iSe.-, 'it may have two 'side-by-side annular trac'ks. Reference numbers 22 and 23 are interconnected collector electrodes. On the back side of the target electrode, there 'is provided'a metallic annularsignal plate 25 which is returned to'g'rou'nd potential via a resistance 26. When the reading beam sweeps over the target electrode, the signal voltage regained from storage will cause a voltage "drop 'acrossfthe resistance 26. Obviously, the various design :possibilities for the target electrode, as shown in Figure 1', "may, likewise, be applied to the annular target electrode illustrated in Figure-2.

The storage tube according to this invent-ion has the advantages of linear relationship between the amplitudes of the inputsignal voltage and'tho's'eofthe-output signal voltage since, as has been known per se, electrostatic defle'c'tion is linear. Moreover, the range of intelligence which can be stored-may be of almost any magnitude, due to the scanning principle accordin'g to this invention. Since th'e mean "intensities of both the writing beam and the reading beam are kept constant, the working :point on the characteristic curve which ''is most favorable for the deflection can always be "adjusted independently of the input signal. Last, but not least, the system accordterized in that the electron beams have band-like crosssectional shapes with the longer transverse beam divmension disposed transversely of the longitudinal dimension of the target electrode over which said electron beams are swept; beam deflection means acting on the writing beam for deflecting the latter transversely of the target electrode in response to signals to be stored there- 'on so as to position-modulate the writing beam, and said beams having a constant mean intensity over each swept cycle.

2. A signal storage tube, as set forth in claim 1, characterized in that the target electrode comprises two parallel tracks the width of which at least equals the longer cross-sectional dimension of an electron beam, the electron beam sweeping along one track when undeflected and being displaced at least partially onto the other track when deflected.

- Y 3. A signal storage tube as set forth in claim 2, characterized in that one track comprises a collector electrode, while the other'trac'k comprises a storage electrode.

4. A signal storage tube as set forth in claim 2, characterized in that the two tracks comprise electrically mutually insulated storage electrodes.

5. A signal storage tube as set forth in claim 3, characterized in that the two tracks have been arranged closely paralleltto one' another and mutually electrically insulated from each other.

I 6. A signal storage tube as set forth in claim 3,.

characterized in that the two tracks have been arranged fat a small distance from one another and electrically insulated from each other.

7. A signal storage tube as set forth in claim 2, charac- .terized in that the target electrode has a single storing layer comprising both tracks.

8. A signal storage tube as set forth in claim 1, charac- 6 V, terized in that the intensity of the beam us'ed for the writing cycle is differentfrom the intensity of the beam used for the reading cycle. y i

9. A signal storage tube'as set forth in claim 1,- characterized in that the beam cross section during thereading cycle extends transversely of the target electrode'at least twice the width of one track.

10. A signal storage tube as set forth in* claim 1, characterized in that the target electrode is annular and normal to the axis of the gun.

11. A signal storage tube as set forth in claim 10,

characterized by beam-shaping means between thesweep means and the target electrode for distorting the beam emitted by the electron gun from a beam of circular cross section into an elongated beam, the longer dimensionof which is radial as applied to the annular target electrode; and said beam deflection means comprising annular de-V said radial fiecting electrodes for deflecting the beam in direction. a

12. A signal storage tube as set forth'in claim 11,

characterized in that the beam-shaping means comprises an annular cylinder lens.

13. A signal storage tube as set forth in claim 11,

characterized in that said deflection means comprises annular concentric deflection plates.

14. A signal storage tube as set forth in claim 13,

characterized in that said deflection plates compriseiseveral separate sections for the purpose of improving the sensitivity of deflection.

15. A signal storage tube as set forth in claim .11,

characterized in that the deflection means comprise several pairs of concentric truncated surfacesotrevolution disposed in spaced relation along the tubeathe directly concentrically adjacent parts of which are applied to the same potential; and that the parting lines between the pairs have been designed such, that the beam will be subject to deflection if there are diflerent voltages on said j spaced pairs. 7

References Cited in the file of this patent UNITED STATES PATENTS 2,276,359

Von Ardenne :'Mar.' 17, 1942 2,887,612 Frenkel May 19, 19 59

Images