Патент USA US2099749код для вставки
Nov. 23, 1937. ' R. T. ORTH ELECTRON TUBE 2,099,749 ‘ Filed May so, 1935 2 Sheets—Sheet' 1 4 5a. 17" .50 129.51; _"-__ ' // 14 70 / 129.54 ‘a /4 /3 /4 /3 //0 \OPM /70 /z/ 10 ’ INVENTOR 7-“ RICHARD T. ORTH 12 BY ATTORNEY ' Nov. 23, 1937. Y R. 'r. ORTH ’ 2,099,749 ELECTRON TUBE Filed May 30, 1933 > 2 Sheets-Sheet 2 a 4\ 534/ I [49.5 32" 53§ 3/-\ 4a \ 47x INVENTOR RlCHARD ' BY? - , ORTH M44, A‘TTORNEY Patented Nov. 23, 1937 2,099,749 UNITED STATES PATENT OFFICE 2,099,749 ELECTRON TUBE Richard T. Orth, Orange, N. J., assignor to Radio Corporation of America, a. corporation of Delaware Application May 30, 1933, Serial No. 673,572 3 Claims. (Cl. 250-275) This invention relates to electro-optical de vices and systems and more particularly to the use of a cathode ray tube frequently referred to as a Braun tube in connection with such systems. In the prior art the cathode ray tube used for television and oscilloscope purposes usually em ploys a translucent screen which has the prop erty of ?uorescing when subjected to the bom bardment of an electronic beam. In cases where 10 it is desired to producevariations in intensities of the resulting ?uorescent effects, which varia tions might be in accordance with variations in photoelectric currents resulting at a point of transmission in accordance with the scanning of 15 a subject of which the electrc-optical image was One of the more important reasons is ' time, been practically universally adapted, it nevertheless has the inherent disadvantage that upon impressing various voltages or biasing po tentials to produce the control action the effect 10 is that of changing the cross-sectional area of the electron beam, as will become more apparent from what follows. Cathode ray tubes, as designed for television work, reference being made herein to the subject 15 desired, the beam may be modulated by means of television merely in ‘order to illustrate one of an electrostatic control electrode or grid which suitable use for a type of cathode ray tube and control therefor, as herein disclosed, are usually characterized by a long tubular neck one end of which carries the base of the tube and the other a N, conical portion terminating in a section whose 0 normal projection is perpendicular to the axis of the tube. This section is usually concave on the inside, although for small tubes especially it may is disposed in the path of the electronic beam di— rected toward the ?uorescent viewing plane. The control electrode or grid is biased under the in 2 O ?uence of the photoelectrically controlled signal eifects to vary the degree of ?uorescence. According to still other arrangements of the prior art, it has been proposed to control the in 25 another. that the intensity controls of the types above outlined frequently cause the effects of streaking or the like in the view-ed electro-optical effects produced from screen ?uorescence. 5 While the grid control has, up to the present tensities of the observable effects upon the ?uorescent end wall of the cathode ray tube by de?ecting the cathode ray pencil with respect to an aperture or opening in a screen plate or with respect to a limiting or beam de?ning edge of a screen plate which is opaque to the passage of 30 the electrons. This type of prior art arrange ment functions so as to control variably the num ber of electrons which pass through the opening ’ or past the beam de?ning edge of the shield. Still other arrangements of the prior art have 35 provided for intensity control of the fluorescent e?ects by a variation in the velocity of impact of the electron stream upon the ?uorescent screen. Other arrangements operate to control the ob servable intensity of the ?uorescent spot by varying the velocity of traversal of the cathode ray stream projected at constant instantaneous impact. velocity upon the ?uorescent viewing plane so that the variations produced in the pc 45 riods of actual impact of the cathode ray beam 4 at any diilerential area upon the screen produce the e?ects of varying lights and shadows from the resulting light spot, the intensity of ?uorescence being a function of both velocity of impact and 50 time of impact. All such arrangements of the prior art while, in general, satisfactory, particular reference be ing made to the grid control effect so universally used, nevertheless are somewhat unsatisfactory 55 for extremely accurate control for one reason or be ?at or even convex, and is provided with screen structure of a ?uorescent character upon which the cathode ray stream or pencil impinges. The pencil or beam of rapidly moving electrons has its origin in a heated cathode or, where desired, even a cold cathode located at the base end'oi' 0 the tube. From the point of origin of the oath ode ray beam or pencil to the point where it strikes the ?uorescent screen the beam is con trolled by either electrostatic or electromagnetic ?elds or both so arranged as to accelerate, focus 35 and de?ect the cathode ray pencil in the direc tion or directions desired. One suitable means for de?ecting the cathode ray beam is by the use of electrostatic de?ecting plates conveniently located in the neck of the tube, or, where desired, externally of the tube. An electrostatic ?eld produced between these plates upon the application of voltages of suit able frequency thereto produces an acceleration of the beam in line with the ?eld between the plates. For television work two sets of de?ect ing plates may be used and, if so, the surfaces of each set are at right angles to each other. Such an arrangement permits de?ection of the cathode ray pencil in two planes perpendicular to each other but both normal to the axis of the tube. Where desired, of course, it is possible to substi tute electromagnetic de?ection for the electro static de?ection hereinabove suggested and it has been found in many instances desirable to com- 40 45 50 55 2 2,099,749 nal sections of the electrode structures shown by ' bine electromagnetic and electrostatic de?ection systems; Figs. 3a and 3b; Fig. 4 illustrates a modi?cation of the invention in which a double helical heater and unipotential type cathode is provided with a hollow core and an electrode in positiontwithin the cathode mem 7 To controlthe intensity of the cathode ray thus de?ected and positioned upon the tube screen, according to the prior art, the electro static or grid control consisted in an electrode member substantially surrounding the electron ber; Fig. 5 illustrates a mandrel suitable for form- ' ' emitting area. in such manner that the issuing ing a unipotential cathode heater shown by Fig. 4; electrons were drawn through an aperture of Fig. 6 illustrates conventionally a cathode ray 10 predetermined size. Modulation of the cathode ray beam to vary the intensity of the resulting ?uorescent effects was accomplished by varying the negative bias. With zero bias on the grid electrode the effective aperture has been found tube assembly omitting the enclosing envelope and comprising the cathode‘ of Fig. 4 and the helical heater assembly together with related electrodes adjacent thereto; and Fig. 6a illustrates the cross section of the elec tron beam at the line B—-B of Fig. 6. 15 to be the same as the actual aperture. However, as the negative bias is increased the effective di ameter of the aperture in the control grid mem The general type of cathode ray tube used for ber decreases with the result: that the size of the television purposes is similar to that shown by Fig. 1. vThis tube, as has been above stated, is spot on the screen decreases in diameter. In tele 20 20 vision seanning this will result in a variation in characterized by a long tubular neck portion I the light spot diameter with each change in, upon one end of which is supported the base 2 ' modulation. and the other a'conical portion 3 terminating in ' a ?uorescent screen 4. The cathode rays are This effect then becomes observable in the form of dark lines on the ?uorescent screen generated within an electron gun structure des because the line de?nition at all times throughout 25 the scanning period remains constant. I ignated as 5 and the rays or electron stream thus It is',._ therefore; one of the primary objects of . developed and projected toward the ?uorescent this invention to overcome this changing spot size screen member 4 may be suitably de?ected by applying suitable controllingv voltages in'the elec trostatic de?ecting plates 5 and to a secondv set of plates (not shown) arranged transverse to the 30 set of plates 6. Of course, magnetic de?ection or a combination of electrostatic and‘ electromag defect and to producea scanned area on the ?u crescent viewing screen which is devoid of all so streaked veifects. . . Still other objects of the invention are to pro— vide more suitable means for controlling the den sity of a beamrof electrons. ~ I Another object of the invention is to provide means by which a beam of electrons may be mod ulated and controlled by suitable controlling elec trodes without in any way‘a?ecting the operation :35 V netic, provided the electrostatic de?ecting mem bers are formed from non-magnetic material so as not to be subjected to the in?uence of the magnetic de?ecting materials; might be used. . According to the conventional type of cathode or changing the actual diameter of the resulting ' ray tube design a control grid member, such as area of ?uorescence upon the viewingscreen. Other objects of the invention areto provide 40 the structure Ill shown by'Figs. 3a and 3c, is usually arranged to surround substantially the 40 modulation or control arrangements for varying the intensity of a cathode ray pencil of electrons in whichthe control is more sensitive than that found in‘ arrangements heretofore used in the 45 prior art; to provide a control system which is extremely simple in its arrangement; to provide a control system which readily adapts itself to ture as is used in the cathode ray tubes ,now . use in connection'w'ith cathode ray tubes of the present type so that it will be unnecessary to re-' conditions of zero bias on this controlielement ' design the general structure of the tube; and to provide a control system that is extremely e?i cathode ray stream I5 is adapted to pass is the 50 cient in its operation. cathode emitting surface and the» developed elec trons are projected toward the ?uorescent screen structure 4 through the aperture l I. Such struc usually known varies the modulation of the beam or electron stream by varying the negative bias applied to the grid or control electrode 10. For 4.5 Ill the’ e?ective aperture through which the » same as the actual aperture ll so that the oath-1 ode ray pencil emerging from the grid structure I V ' 'Still other and further objects of the invention ' will become apparent and suggest themselves to 55 those skilled in the art to which the invention will have an actual electronic diameter equal to ' the diameter of the aperture H.’ However,, as relates from reading the following speci?cation the negative bias is increased to vary the intensity of the resulting electronic light spot on the and claims in connection with the accompanying ?uorescent screen structure the effective diam- t drawings, wherein: m ' ' " V Fig. 1 illustrates one type of cathode ray tube 60 to which this invention is applicable}. > Fig. 2 illustrates. one form of electrode struc V ture which may be enclosed within the tube shown by‘ Fig. 1; ' , I Fig. 2a represents a transversesection through 65 the electron stream on the line‘ A-—A; Fig. 3 shows various forms of modulating elec trode which’may be'incorporated as apart of the electrode structure within the ‘tube of Fig. 1;' eter of the aperture 1 I decreases due, for example, to repulsion of theemerging electrons from the edges of the diaphragm member, so that the spot; size also decreases. This e?ect produces, as has‘ been above de?ned in the statement of invention, dark lines on the ?uorescent screen because the line de?nition remains, always constant. ' ' According to the present invention these above 6-5. mentioned difficulties have been substantially overcome by changing the control electrode struc ture to some extent from the form now used inv ' -~ Fig.'3a designates an electrode structure having ' 7 tubes known in the art. In the new form of the a circular aperture across which the control ele- ' ment is provided; ' . Fig.f3b indicates an'electrode structure with a 75 control electrode herein disclosed the control electrode structure includes the disk or plate square aperture controlled similarly to the ar member in formed with the shielding structure 7 rangement of Fig. 3a; l2 attached theretoso that it resembles closely the usual grid structure 10 above discussed but’ ‘ ' ' Figs. 3c and 3d respectively vindicate longitudi is 2,099,749 is distinguishable therefrom both in formation and operation as will herein be pointed out. As ‘shown by all of Figs. 3a through 301 inclusive, the aperture of the control electrode 10 may be round, as shown by the apertures ll of Figs. 3a and 30, or square, as shown by the apertures l3 of Figs. 3b and 3d, or may be of any other suit able formation. In addition, the aperture should be formed slightly larger than the aperture in the 10 regularly used control elements wherein the light spot diameter depended upon the aperture diam eteri Across the aperture H or l3 in such man ner as to divide the area of the aperture into two substantially equal parts there is attached to 15 either side thereof, by welding or by other suitable means, a wire M which is stretched and forms electrical contact with the disk surface 10. The effect of this design, as can be seen more particularly from Fig. 2 of the drawings and 20 also from Fig. 2a thereof, is to control the cen ter of the electron pencil or beam l5, which is developed by drawing the electrons issuing from the electron emitting surface I‘! of the heated cathode member l8 by means of the application 25 of suitable positive voltages upon an anode elec trode [9 for example, rather than to change the beam diameter as is the case when modulation is produced by the usual type of control electrode. The apertures I! and I3, depending upon the 30 shaping of the disk member as in Figs. 3a and 3c, are so large that little or no current will be cut off from the outside of the electron beam and the wire l4 stretched across the aperture will cut a diametric swath from the beam 15. As the bias 35 on the control electrode comprising the disk mem ber l0 and. the shielding portion I2 is increased negatively the apparent size of the wire l4 as re gards the control of the electron beam will in crease. This effective or apparent increase in the size of the wire l4 causes a reduction in the number of electrons forming the central portion of the electron beam or pencil l5 which passes through the aperture 20 of the disk member 2| forming a part of the anode structure I9. This 45 effect, in turn, results in an electron stream which takes the general form of the aperture 20 of the 3 hollow along its axis A-A. The electrode mem ber 40 is so formed as to extend beyond the continuous end of the ?lament 34. To the end of the electrode 40 nearest to the terminal mem bers 35 and 36 of the ?lament 34 there is at tached a suitable tab or contact member 39 to which electrical connections may be established. In manufacturing a ?lament of this general type the ?lament is wound upon a mandrel such as that shown by 42 in Fig. 5. This mandrel is 10 formed preferably of molybdenum and provided with a double helical groove 43. A tip portion 44 is machined on the end of the mandrel to. pre vent the wire which is wound thereon crossing the -axis of the coil. This suggested method of 15 winding is merely illustrative since there are various suitable methods for performing this op eration. ' Following the winding of the ?lament it is covered with a layer of insulating material which 20 is baked by suitable heat treatment. The elec trode 40 which will constitute the control elec trode and which can be seen in its assembled form from the showing in Fig. 6 is also coated with insulating material and baked whereupon 25 it is inserted into the coil so that the contactor tab portion 39 lies at the same end as the lead wires of the ?lament 34. This assembly is suit ably inserted into the cathode sleeve portion 31 which is provided with a conducting tab portion 30 4i electrically connected thereto by welding or other suitable means. The cathode sleeve portion 31 is provided with an aperture 38 of suitable diameter through which the electrode member 45 protrudes. The annular face 45 of the cath 35 ode sleeve 31 is coated with a thermionically ac tive substance prior to the assembly operation so that upon heating the cathode member by the application of current to the terminals 35 and 36 of the ?lament 34 electrons are emitted from 40 the activated surface of the annular face 45 to form an electron beam 46. This electron beam 46 is suitably controlled, limited and focused by the electrodes 49, 411, 48 and 33. The function of the electrode 40 is similar 45 to that of the wire I 4 of Fig. 2, in that, its pur electrode l9 except that the fluorescent spot pro pose is to modulate the cathode beam or pencil duced upon the ?uorescent screen structure 4 is 46. However, with the arrangement shown by Figs. 4 through 6, and more particularly by Fig. divided by the wire member 14 into two parts as 50 can be readily appreciated from an observation of Fig. 2a which represents a cross-section through the electron stream on the line A-A intermediate the aperture 20 and the screen struc ture 4. From what has been above stated, it 55 will be appreciated that the wire l4 effectively casts its shadow upon the screen structure 4 but this shadow is not in any way detrimental to any detail of the area scanned provided that the electron beam is swept back and forth across the 60 ?uorescent screen structure in such manner that the resulting shadow or dark line produced is perpendicular to the direction of beam motion. It is also possible in accordance with the teach ings of this invention, disclosed especially by Figs. 65 2 and 3, to modulate the electrons emanating from the heated cathode in still another manner in accordance with this invention. In such form use is made of a double helically wound ?lament which is hollow along its axis. With such a con 70 struction a rod-like electrode is then supported within the hollow portion of the ?lament mem ber. Such a construction is shown more partic ularly by Fig. 4 which represents the various companion parts of a ?lament assembly. 75 In Fig. 4 the filament 34 is formed so as to be 6, it will be seen that the cathode ray beam or 50 pencil 46 is similar to a hollow cylinder as shown by the section through the beam taken on the line B—B, whereas the cathode ray pencil l5 of Fig. 2 has a cross—section which consists sub stantially of two areas bounded by semi-circles. 55 In the operation of the arrangement shown by Fig. 6 the electrode member 40 tends to spread the cathode ray beam 46 with any increase in negative potential. If the anode element 33 has a ?xed aperture 3| provided at one end thereof and has a 60 constant positive potential impressed thereupon the beam passing through this aperture will at all times be constant in cross-section regardless of the potential impressed upon the modulating elec trode 4B. The electrode 33 will collect any of the 65 electrons which may have been spread out to cover a larger area than that of the aperture 3|. Thus, modulation of the cathode ray beam may be ac complished without changing its diameter or boundaries. The luminescent spot produced upon 70 the ?uorescent screen structiu'e 4 will then be of uniform size, that is, the boundaries will at all times remain constant, regardless of the modulat ing voltages impressed thereon. The cathode ray spot thus produced and con 75 wad-14.0 ' trolled or modulated may be, focused 31)“! the screen structure in such a way as to eliminate the dark spot which would naturally be expected from ‘ the hollow nature of the beam. This focusing C21 action may be accomplished. by impressing suit able potentials upon the first and second anode members .33 and 33a, respectively. As shown by ' Fig. 1', for example, the conical portion 33 of the tube member is formed of conducting material 10. and suitable voltages may be applied thereto by ' Way of the metal cap 50 formingcontact there thereon, means forv maintaining . constant the. _ bounding area of instantaneous impact of electron stream upon the screen to maintain a constant outer boundary of the resultant luminous effect, and a control electrodelocated within the outer boundary of the electron source electrode for reducing the electron density of, the projected‘ electron stream withina central portion of the boundary limits to produce an annular shaped electron stream with a constant outer diameter .10 and a variable inner'diamet'er so as to vary there with in any suitable manner, such as shown for ‘by’ the observable intensity of the luminous effect f example by my copending application, Serial No. produced. 2. An electron tube which comprises an emissive 643,955, ?led November 23, 1932. Other voltages surface electrode serving as, a source of electrons, .115, for operating the tube are-applied to the tip mem bers or contact points 5i formed as a part of the base member 2, except that it isusually preferable a ?uorescent screen coating on the inner surface of the tube end wall opposite the electron emissive ' to make electrical contact to the de?ecting memV-V , surface, means for causing the electrons generated > at the’ source to pass toward the ?uorescent end ‘ bers such as the de?ecting plates 6 at points sub 20 stantially adjacent these members byway of lead wall of the tube as a pencil of electrons, means for 2,0 maintaining the bounding area of‘ the electron passing through the tube wall at points closely’ pencil ‘developed constant, means for causing the electron pencil to traverse the ?uorescent screen adjacent to the'de?ecting members. ' Without departing from the spirit and scope of 7 according to a predetermined pattern of traversal, and a control element protruding beyond the cen- : 25 this invention it will be apparent that otherrand tral portion of the electron sourceandlocated various waysand means may be provided for con within the outerboundaries of the emissive sur trolling the intensity of the ?uorescent spot re wires connected to the de?ecting elements and sulting upon the, ?uorescent screen of a cathode face electrode, said element adapted to have yary- . 7 ray tube or other type of electronic device where? ing voltage applied thereto tovary the electron density within, a central portion‘of the electron 30 in the effect of variation in the size or diameter of the resulting ?uorescent spot is avoided, and vI beam to vary the intensity of luminescence pro there-fore believe myself, in accordance with the :duced over a substantially constant area of the ?uorescent screen. . . 1 modi?cations of this general scheme herein sug v3. A cathode ray tube comprising a surface for ' gested, to be entitled tomake and use any and . emitting a stream of electrons, a target positioned 35 35 all of these modi?cations which fall fairly with in the spirit and scope of the invention asset in the stream and adapted to luminesce under im ' pactof the electrons, means to focus the emitted forth by theappended claims. I Having thus described the invention, what I electron stream on the target_,‘means to limit and claim and desire to secure by Letters Patent is the ?x the boundary area of the instantaneouslyim following: . 1. An electron ‘device including an electrode serving as an electron source, means to cause the electrons emitted to be projected along a prede pinging electrons and electrode means acting only ( within the ‘emitted electron'stream to variably re- ' move under the control of signals the electrons from the inner portion of the boundary area of:v ' termined path, an observation screen in the path . impact to vary the intensity of the luminescent of the projected electrons adapted to become luminescent when the projected electrons impinge effects produced. ' . I RICHARD T. ORTH. '