US2616060A - Cathode-ray coding tube - Google Patents

Description

Oct. 28, 1952 I W, M, GOODALL 2,616,060

CATHODE-RAY CODING TUBE Filed July 5, 1948 Arrow/VE;I

Patented ct. 28, 1,952

UNITED STATES PATENT OFFICE 2,616,060 yolfl'rHoDE-Imr CODING 'ruins` William M. Goodall, Oakhurst, N. J., assigner to Bell-Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application July 3, 1948, Serial No. 367,035

9 Claims.

`deflecting in one direction under control of the amplitude of the complexv wave form and is caused to move across the target or aperture plate in another direction across apertures in the target. The target is formed so that the beam in sweeping across the target will form code groups of pulses of signaling conditions depending upon the apertures through which the beam passes.

In such a tube it is first necessary to position the beam in one direction and then'maintain the position in this direction while the beam is moved in another direction. Thus in'order to form a code group it is necessary to successively move the beam into different directions. All these operations require appreciable time and the code is never complete until a beam completely sweeps across the entire target for a given signal amplitude.

The object of the present invention is to provide an improved cathode ray tube which operates ata high rate of speed and which continuously provides at its output terminals a complete code group of signaling conditions'representing the instantaneous amplitude of -a complex wave form. I

One feature of this invention relates to a coding tube which operates continuously to supply to the output circuit code groups of signaling conditions under controlof an applied complex wave form in which the code groups of signaling conditions `are all changed simultaneously and which all represent the instantaneous amplitude of complex wave forms at substantially all times.

A feature of this invention relates to a translating and coding tube in which it is necessary to move the beam in either direction along one line which usually forms one of the axes of the output electrodes.

A feature of this invention is to provide a translating or coding tube which will form or generate the same code group'of signaling conditions for amplitudes beyond or in excess of the limits of the normal operating range of the tube which are the same asv theV codes representing the limiting amplitudes of the normal operating range. f Y Y Y f Another feature of the invention relates to a modified target in which some apertures in addition to the end apertures are elongated to suppress noise, to` clip, compress or otherwise modify the complex YWave Vform or the signals transmitted representing it. .f

Another feature of this invention relates to auxiliary beam positioning apparatus comprising additional apertures in the target and means and interconnections for the deflecting beam to cause the beam to occupy a position over a given group of apertures `and to prevent the beam from occupying a vposition between groups of apertures representing different codes. i

Another feature of this Vinvention relates to the cathode ray tube in which the electron .beam is in the form of asheet or plane electron which is focused by means of apertures and other beam forming elements in a narrow line across target plate. Defiecting means are provided for moving said beam relative to the aperture plate so that it passes through different code groupsof apertures of said target plate.

Another feature of the invention relates to a plurality of collective electrodes arranged behind apertures in said aperture plate to collect electrons passing through said apertures of the aperture plate or target.

Briefly, in accordance with the present invention the cathode ray tube comprises a source of electrons, beam forming and focusing elements for forming a iiat beam of electrons and focusing them in a narrow line upon a target Yor'aper ture plate, ,deecting means for deflecting the beam over said aperture plate, and an aperture plate provided with code groups of apertures formed therein.

While the apertures may be formed in the aperture plate in any predetermined manner according to any desired code or in a random fashion, in the specification embodiment set forth i herein the apertures in the aperture plate are arranged to form a binary number system or code wherein the apertures are arranged in columns and each aperture in the ,iirst column represents the magnitude of one unit of amplitude of a complex wave form. Each aperture in the next column represents two units in the instantaneous magnitude of the complex wave form. The aperturesin the third column represent four units and each aperture in the fifth column represents eight units, etc. Anauxiliary group of apertures and an auxiliary electrode behind these auxiliary apertures are arranged to prevent the electron beam from coming to lrest between two groups of apertures in the aperture plate.

The foregoing objects and features of this invention, the novel features of which are specifically set forth in the claims appended hereto, may be more readily understood from reference to the attached drawings in which:

Fig. l illustrates an exemplary form of cathode ray tube for representing instantaneous amplitude of the complex Wave form by means of code groups of signaling conditions; and

Fig. 2 illustrates a modified target.

Such types of signaling circuits and apparatus are frequently called code modulation systems and the code employed in the exemplary embodiment set forth herein is sometimes called a binary code.

A tube of the type described herein is suitable for use in combination with the other circuits in my copending application Serial No. 67,211 filed in the United States Patent Oice December 24, 1948.

The coding tube in accordance with the p-resent invention is also suitable for use in combination with the other systems and circuits described in an application of J. C. Schelleng, Serial No. 677,667 filed June 19, 1946, now. Patent 2,453,461, granted November 9, 1948 disclosure of which application and patent is also'hereby made a part of the present applicationas if set yforth herein in full.

As shown in Fig. 1 of the drawing the tube comprises an evacuated envelope I which may be of metal, glass or other suitable material including combinations of metal, glass or other suitable materials usually employed in the construction of evacuated electron tubes and devices. Cathode II of the tube provides a suitable source of electrons when heated to the proper temperature by means of the heating element supplied by suitable power through transformer I8 in the usual manner.

Three beam forming elements I2 are shown in the drawing. The beam forming elements may be of any desired or suitable number and 'may be of any desired shape or conguration. These elements and apparatus herein provided are connected to suitable sources of accelerating and beam forming and focusing potentials such as sources 28 and 27. Sources 27 and 28 are illustrated as batteries in the drawing and may comprise rectiers, lters, or any other suitable power sources or generators.

In accordance with the present invention the beam forming electrodes I2 are arranged to form a wide beam or plane of electrons of very small thickness which is focused upon the target I1. The beam forming elements I2 may be equipped with apertures in the form of slits instead of small holes as in the usual case so that these beam forming electrodes will function analogous to cylindrical lenses instead of analogous to circular or spherical lenses as in the usual cathode ray tube wherein the electrons are focused to a small spot or point on the screen or target.

The beam forming members as shown on the drawing are intended to represent or include magnetic beam forming focusing fields, coils` and related elements and apparatus. Thus the beam forming and focusing may be electrostatic, electrcmagnetic or a combination of both types of electron control means.

Target I'I is providedwith a plurality of apertures arranged in columns and rows as shown in the drawing.

target in different positions.

The coding and translating tube described?. herein is arranged to represent the amplitude: of the complex wave form by means of code: groups of signaling conditions. Each code group,- comprises a plurality of independent signals eachsignal of which may be any one of a plurality of different signaling conditions.

In the exemplary embodiment described herein the target is arranged to represent the amplitude of the complex wave form at rapidly recurring instants of time by code groups of five diiferent signals. rThese signals may be of either one or the other of two different signaling conditions.

The invention is not limited to code groups of I five diierent signals but may employ code groups of any number of signals each of which may comprise any number of signaling conditions.

In order to more readily describe and follow the various signaling conditions these two signaling conditions are frequently called a mar-king signaling condition and a spacing signaling condition; they are some times called on signals and off signals; other times they are called signals of current and no-current; other times they are called signals of one polarity, say positive, and signals of a negative polarity or voltage. These signals in being transmitted through the various circuits and apparatus of the system may change their form from current to no-current, from positive to negative, etc. As a result it is frequently more desirable to refer to them as marking signals or spacing signals 0r on signals or off signals.

It is to be understood that the target may be arranged to employ more signal elements in each code combinationand that the signal elements of these code combinationsmay comprise any one of more than two different signaling conditions. However, in order to more readily understand the invention the code employed in the exemplary embodiment described herein is one in which each of the elements-may comprise either one or two different signaling conditions in the exemplary embodiment set forth herein.

As shown in the drawing, theaperture plate I7 is arranged to form vcode groups of signaling conditions in accordance with binary number system. The first column of apertures 35 represents one unit. When the beam passes through an aperture in this column and some electrons fall upon the electrode 25 it represents one unit of the amplitude of the complex wave form. When the beam passes through an aperture in the column 3l! it represents two units of the amplitude. When the beam passes through an aperture in column 33 it represents four units. Likewise each timeit passes through an aperture in column 32 it represents eight units and when it passes through an Yaperture in column 3| it representssixteen units ofthe amplitude of thecomplex wave form. The total amplitude of the complex wave form is thus represented by the sum of the magnitudes represented by the apertures through'which the beam passes.

Defiecting plates I3 and I4 are provided and connected through transformer I9 to a source of signals or complex waveforms to be represented by the code groups or signaling `conditions. These plates Yare arranged to deflect'the In accordance with the ex emplary embodiment set forth herein the apertures in target I'I are arranged to form the de sired code when the beam impinges upon the.

beams vertically as shown in the drawing. While the beam is shown deflected in the drawing by the electrostatic plates I3v and I4, these plates may -be replaced .by electromagnetic deflecting lcoils and means asis well understood in the art.

As shown in the drawingthe beamis focused.

in a horizontal line across .the target plate I1 and deflected vertically, that is, at right angles to the lineof the beam underv control of the appliedsignals. When the signals are of a minimum amplitude the beam :will be deflected toward the lower part of the target plate. When the amplitude oi the complex wave form is near the average value the beam will be near the middle of plate I'I. When the amplitude of the complex wave form approaches a maximum the beam is moved up near the top of target plate I1.

When the beam is in its lowest position the beam will not pass throughl any apertures in the aperture plate. It may -be desired to extend the plate somewhat further downward so that for all amplitudes less than a predetermined minimum the same code combination, in which the beam does not pass through any of the apertures, is generated in the output; circuits of the tube. In the iirst position. above this position the beam will pass through the lowermost aperture in column 35 thus indicating one unit of amplitude of the complex wave form above the minimum amplitude.

The apertures in the target plate are described herein as arranged in rows and columns. It is evident that by rotating the tube through 90 degrees the rows become columns and the columns rows so that the rows and columns are interchangeable.

Also in the exemplary embodiment set forth herein, an aperture plate is provided in combination with collecting electrodes behind the apertures. It is evident that an equivalent group oi properly shaped and proportioned collecting electrodes can be employed when desired.

In the second position from the bottom the electron beam will pass through an aperture in the second column 34 thus indicating two unitsl of amplitude above the minimum. In the third position the lbeamY will pass through an aperture in the rst column 35 and another aperture in the second column 34 thus indicating three units of amplitude. In the fourth position the. beam will pass through an aperture in the third column 33 indicating four units of amplitude. In each one of the succeeding positions the beam will pass through apertures-'in the various columns indicating the units of amplitude of the applied complex signal wave. As is pointed-out above. the plate may be extended an appreciable distance below the lowermost position of vapertures so that should the beam be deflected downward to a greater extent than normal the samecode combination as the last lowermost position wherein the beam does-netpass through any apertures will still be maintained on the output electrodes.

When desired, additional elongated apertures may be provided in the target plates which may be extended by greater or lesser amounts as may be desired. These additional elongated apertures may be positioned near the center of the plate to 1 number of codes.

`eficacia. noise .suppression or .Y at. any.; other :intermediatejposition for otherspecial purposes including limiting, clipping, compression, expansion.etc, u l

Fig. 2, for example, shows a modified target plate in which one set of code aperturesy has been elongated so that so long as the beam remains in this small center rangethe same output code is applied` to the output electrodes. In this manner small noise potentials or voltages are all represented by the same code and thus eiectively suppressed. However., when vvsignals having, a

greater amplitude than the normal noise ampli- .tude are applied to the deiiecting Usystem orfthe .tube theywillpause the tube to operate` in thev lmanner vdescribed above and transmit or generate code groups representing the amplitude of the applied signal wave.` As shown in 'Fig.m2, the end apertures are also elongated so thatthe tube will operate as described above when abnormally large signaling amplitudes are applied to the tube.

When desired, the aperture may be made tobecome progressively larger or progressively smaller as the amplitude of the applied signaling Wave is increased. In the rst case, the applied wave form is effectively compressed so that a larger signaly amplitude may be represented by a given In the second case, the compleX wave form is effectively expanded. Likewise, the uppermost apertures may be extended for an appreciable distanceabovethe last normal position of the beam so that in case it is deflected in an abnormal amount upward the same code combination wherein the beam passes through an aperture in each one of the coding columns will be continued even for the abnormal deflection of the beam by an abnormally strong signal wave applied tothe deecting plates I3 and I4.

It should be noted that the proper biasing voltages as well as the signal voltages,y described above, are applied to the deflecting plates I3 and I4 so that the voltages of these plates do not interfere with and may aid in the focusing of the electrons in a narrow line upon the target I1.

The electrons which pass through apertures in the target plate in accordance with any suitable type code such as that described above, will Vfall upon thecollecting electrodes '2I through 25, inclusive, positioned behind the respective columns of apertures 3i through 35, inclusive. When elec trons fall upon these collecting electrodes they cause a change of potential of the respective` electrodes. If the electrodes act as normal collecting electrodes, their potential will fall or become more negative in response to the electrons'which fall on these elements. If, on the other hand, the elements 2 I. through 25, inclusive, act as secondary emitters thenwhen the primary electrons from the beam impinge upon them they will become more positive.

In either case, it is evident that the potential or voltage of these electrodes is one value when the electron beam does not fall upon them and is another value when the beam does fall upon them. Thus, the voltage'oi these velectrodes con-A tinuously represents the magnitude of the applied complex wave form applied to the deflecting plates I3 and I4. Thus, except for the time during which the beam is passing from one row of apertures to another, the potential of the output electrodes 2I through 25, inclusive, continuously represents the magnitude of the applied complex wave form. It should also be noted ceived by it. Aof the auxiliary sets of collecting plates I5 andas aperture plate Il. y jag'e's of the output electrodes 2| through 25, in-

f'causin'g no V'potential on-the output leads orcausing potentials in accordance with two different codes tope-applied' to the output leads vand in order tofreduce the time required for the `electron 'beam Ato be shifted from one row of aperturesto the next an additional set of vcolumn apertures vis provided-in the-target -plate Hand additional fcolle'cting element or` electrode 2B is provided be- `fhi-nd'these additional apertures. 'These additional apertures, a's illustratedin column-30, are

provided between the rows of coded'fapertures for `f'corlmnns l-31 through 35, inclusive. -b'eam of electrons tends to fall between two rows Thus, if ythe fofthe coded apertures in response to the Vapplied signals a` portion of the electrons willpass through one of these auxiliary apertures and cause the collecting element 2li tobecome more negative, for example, due to the electrons re- This element is connected to one 'a-result ltheldeiiecting plate I5 tends to become f more negative and tends to move the beam downward so that it willno longer rest between the two rowsof coding apertures, instead the beam or "the vmajor portion thereof will pass through the apertures in the 'next lower row.

If, lhowever, the signal changes suiiiciently i thenv the Abeam will move very rapidly up to the next row when the signal overcomes the 'effect '1" the potential applied to the yauxiliaryA deflectf ingelements l and I5. The auxiliary' apertures, vcollecting element and the auxiliary deflecting element of the tube described above are frequently called quantizing elements because they ,i

tend -to'cause Vthe beam to occupy discrete positionsfon the target plate Il and thus tend to represent the magnitude of the incoming signal by any one'of a plurality of diferent vdiscrete 'codes representing a particular discrete amplitude ofthe incoming signal. In other words, the

incoming signal is represented by codes of signaling conditions applied to the output electrodes of the Ytube which do not represent a function Awhichrnay be represented by a smooth curve but one having any one of a plurality oi separate and distinct amplitudes.

It vis,of course, apparent that the feed-back connectionor circuit from the auxiliary element 26 to the auxiliary deiiecting plates i5 and i may include suitable types of` amplifying equipment, centering equipment and other control equipment necessary to secure the desired control of the. electron beamso that the major portion oi' the electrons of the beam will always pass 'through some one row of coded apertures in the As a result, the output voltclusive, continuously and at all times ldevelops a group of coded signaling conditions which repre- ,sent vthe magnitude or amplitude of the applied complex wave form.

"What is 'claimed is:

l. A continuous coding tube for continuously representing the magnitude'of an applied signal wavejby means of code groups of signaling conditions'each of `which may be any one of a plurality v'ofr diierent ypotential conditions comprisin'ga source -of electrons, electronbeam `forming 'elementsfor forming athinsheet'of electrons, a2

Vcoding apertured targetiplate having codedapertures arranged inv rows =across said: aperture target plate, focusing means for focusing. the electrons-of-said beam in afnarrow line on saidtarget applied signal wave.

2. AA continuous coding tube for continuously representing the magnitude'or" an appliedV signal wave vby means of coide groups of signalingconvditions of 'one of la plurality of different potential conditions comprising asource of electrons, electron `beam formingfelements `for forming a'pthin sheetfof electrons, an apertured, target vhaving coded apertures arranged rows :acrossvsaid aperture target,;focusing,means for focusingr the electrons of said' beam in a narrow linevof said --target .parallelnto .said rows of apertures', signal vresponsive means, means controlled by said signal responsivemeans for directing saidbeam of electrons to one of .the rows of apertures onzsaid Vtarget representative of a magnitude of thecomfplex -wa've form, auxiliary apertures in said target, an auxiliary 'electrode behind said auxiliary apertures, auxiliary deflecting means, and con- :nectionsv between said auxiliary electrode and said auxiliary deflecting means for preventing the major portions of said electron ybeam from falling between two of said rows of apertures.

, 3.l In an kelectronidischarge tube a;source of '-electrons, means for forming a beam of said electrons and,` focusing vsaid :electrons in a narrow line, a coding target having a, plurality of coded areas arranged in rows and columns, one of whichis paralleltothe line of electrons, signal `responsive apparatus, 4means for applying sig- `nals to :said `signal, responsive apparatus, deecting'meansifordeflecting said line of electrons in va (direction .perpendicular to the said direction of said line of focused electrons, and connections `between saidpsignal responsive apparatus and said Vdeflectirrg means fforfdeilecting said beam of 'electrons an amount which is proportional to the vmagnitudeof `said applied signals.

. 4. YEncan electron discharge tube a plurality of target areas 'associated with output velectrodes arranged in rows'and columns in Vwhich allsaid areas inonerowdiifer in :length inthe direction perpendicular to- Said row vfrom-the areas-in other rows, electron beamslforming and focusing elements fassociatedx'with said tube for forming a beam'and V:focusing itin a narrow lineY across 'rows ofsaid apertures and apparatus yresponsive v to receiving'lsignals for deflecting said beam at right angles-to said line,l and said elongated di- 'rection 5.. A coding tube having-means for generating f signal` amplitudes to cause it to impinge on varl ions portions lof said target, thereby producing codesignals-related to-said deection signal am- .rplitude-,the number and arrangement of said fcoding portions and-the deflecting means being Y eso arranged that each. recognizably different sig- .nalxamplitude within anormal range is translated into a'unique lpulse code group, said target being "characterizedvini-this, that the width of each 'end portion of said target. measured in the vdirection-cof the beam deflection, ysubstantially ..-:exceeds, the width of every other portion, whereproducing extreme deflections, is translated into the same code as an extreme peak within the normal amplitude range.

6. A cathode ray tube and associated circuits for coding instantaneous values of an input wave into 2n codes where n is any integer comprising a supply source for supplying the input wave, means for establishing a beam in said tube, a coding beam interceptor means in said tube having 2n regions upon which said beam selectively impinges under control of the value of the input wave, beam deiiecting means connected to said supply source for eiTecting said control, each region having n portions having one or another of two characteristics, one of which transmits a portion of the beam and the other of which does not, n electrodes lying beyond said beam interceptor means connected to n output circuits each electrode being conditioned to receive a transmitted portion of the beam, whereby said electrodes are impinged upon by said beam in 2n permutations, each different, corresponding to said 2x1 positions.

7. A tube and associated circuits as per claim 6 having position quantizing means consisting of a supplemental electrode, other beam interceptor means having beam transmitting portions to admit a beam to said supplemental electrode, and feedback means deflectively operative upon said beam to control said beam to cause it to jump from one to another of said 2n regions in discrete jumps instead of remaining in between any two such regions.

8. In an electron discharge tube, a source of electrons, a target area, means for forming a beam of said electrons and focusing said electrons in a narrow line across said target area, a target located in said target area having a plurality of diierent types of sub-areas arranged in accordance with a code, means for deriving an output electric condition when said beam falls upon a target sub-area of one type, means for producing a different electric output when said beam falls upon a target sub-area of a different type, signal responsive apparatus means for defleeting said line of electrons across said target area at an angle to said line, interconnections between said signal responsive apparatus and said deflecting means for deecting said beam under control of said signal responsive apparatus.

9. A continuous coding tube for continuously representing the magnitude of an applied signal wave by means of code groups of signaling conditions each of which may be either one or the other of two diierent electrical conditions comprising a source of electrons, electron beamforming elements for forming a thin sheet electron beam, a target area, means for directing and focusing said electron beam upon said target area, a target located adjacent said target area having a plurality of sub-target areas each having one or the other of two different responses to impingement of said electron beam thereupon, means for deriving one of said electrical conditions from each of said sub-areas of one type in response to the impingement of said electron beam thereupon, means for deflecting said beam across said target area at an angle to the line of said beam, signal responsive means, and means controlled by said signal responsive means for controlling said deiiecting means to deflect said beam of electrons to impinge upon a code group of said sub-areas of said target representative of the magnitude of the applied signal Wave.

WILLIAM M. GO ODALL.

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

UNITED STATES PATENTS Number Name Date 2,053,268 Davis Sept. 8, 1936 2,096,653 Soller Oct. 19, 1937 2,257,795 Gray Oct. 7, 1941 2,287,296 Dallos June 23, 1942 2,395,299 Skellett Feb. 19, 1946 2,463,535 Hecht Mar. 8, 1949

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