US2211325A - Oscillograph - Google Patents

Description

y Allg w40- R. H. GEQRGE 2,211,325

OSCILLOGRAPH Original Filed Sept. 14, 1929 8 Sheets-Sheet 1 INVENTOR. Roscoe HENRY @Eon BY All@ 13, 1940' R. H. GEORGE 2,211,325

OSCILLOGRAPH Original' Filed Sept. 14, 1929 8 Sheets-Sheet 2 v Y TTOREY,

llg- 13, i940- R. H. GEORGE 2,211,325

OSCILLGRAPH original Filed sept. 14, 1929 s sham-sheet 4 f v ATTORNEY.

Original Filed Sept. 14, 1929 fl/M/ R. H. GEORGE OSCILLOGRAPH 8 Sheets-Sheet 5 INVENTOR. ROSCOEV HENRY GEORGE ATTORNEY.

' INVENTOR. .SCOE RY GEORGE 'R. H. GEORGE OSCILLOGRAPH originar Filed sept. 14, 1929 s sheets-smet s Aug i3, w40- R. H. GEORGE 2,213,325

SCILLOGRAPH Original Filed Sept. 14, .1929 8 Sheets-Sheet 7 0 Y 6 f77) d INVENTOR. ROSCOE n NRY GEORGE l BY .ff y

e. ATTORNEY.

Aug. 1-3, 1940. R. H. fsk-,0R65L ,2,211,325

' oscILLoGRAPH original Filed sept. 14, 1929 l@sheets-sheet s NVENTR.

ATTORNEY. y

Patented Aug. 13, 1940 UNITED STATES PTT l OSCILLOGRAPH Roscoe H. George, La` Fayette, Ind., assignor to Radio Corporation of America, a corporation of Delaware 29 Claims.

This application is and forms a divisional part of my co-pending application Serial No. 392,591,` led September 14, 1929,' and entitled Oscillolgraphs. This invention relates to oscillographs and has particular relation to cathode-ray oscillographs and systems of electrical connections therefor, whereby transient electrical phenomena and the like may be accurately and efficiently recorded or observed. v

A veryurgent demand for further knowledge of lightning and other transient phenomena, and other high-frequency electrical phenomena in general, has resulted in the development of three general types of cathode-ray oscillographs for such investigations. These types are the highvoltage, cold-cathode type, the low-voltage hotcathode type and the medium-voltage hot-cathode type.

The cold-cathode type of oscillograph employs a gaseous discharge which requires from 30,000 to 90,000 volts to produce the cathode ray or beam.A Because of the high velocity and resultant penetrating power 'of the electrons constituting the beam, this type of instrument has a high sensitivity with respect to the photographic re-.

cording of the movementsl of the cathode ray or beam, but has a low sensitivity with respect Ato .the deflection of the beam to produce the movement thereof Aindicating the characteristics of the phenomena to be recorded or observed. It is also difcult to control the intense discharge of this type of instrument for more than a fraction of a second, and, therefore, instruments of this type are best adapted `for recording phenomena of very short duration only. The cathode ray or beam is also quite sensitive to gas pressure, and is slow to get into operation, which is a material factor in the recording of lightning surges, for example, the time of occurrence of which cannot be predetermined.

The low-voltage, hot-cathode type of instrument, utilizing 300 to 1,000 volts in its operation, has the advantage that the cathode rayer beam can be focused to a well-defined 'spot of .high intensity on the photographic plate or viewing screen. The beam is also very sensitive to deflecting fields and may bemaintained for an indefinite period of time. This type of instrument has the disadvantagephowever, that its photographic sensitivity for 'recording purposes is extremely low.

The medium-voltage hot-cathode type of oscillograph, operated on voltages of the magnitude of 1,000 to 20,000 volts, has the advantages of (Cl. IVI- 95) increased photographic sensitivity and in the fact that the beam may be maintained continuously. The inherent decrease in deflectional sensitivity caused by the increase in voltage necessitates the employment of special means for 5 focusing the beam and for creating the deecting fields in its path of travel. Other diiculties which have been heretofore encountered in the utilization of this type of instrument are the removal of the oxide coat from the hot cathode or filament by positive-ion bombardment and the formation of a gas discharge which produces a large beam surrounding the main beam or cathode ray. J

The primary object of the present inventionis 15 to produce a general-purpose cathode-ray oscillograph of the hot-cathode type, which may have suicient flexibility to be operated over a wide range of voltages and which may still produce an intense, well-focused beam of f high photographic and deflectional sensitivity, combining, as far as possible, the desirable qualities of previous types of such instruments without detracting from the simplicity and reliability of operation heretofore attained.

It is also an object of the present invention to produce an instrument of the above-indicated character that will be robust and reliable in order that it maybe readily adaptable for portable use Without affecting the accuracy and efficiency of its operation.

A further object of the invention is to provide an instrument of the above-indicated character and systems for controlling the operation `of the same, whereby phenomena of extremely short duration and occurring at times which cannot be predicted may be automatically, fully, and accurately observed or recorded.

The oscillograph constituting the invention has been designed and developed with a particular view to gaining the necessary photographic sensitivity through the use of ahigh-intensity cathode ray or beam at a minimum beam voltage. One of the principal problems, then, has been to devise satisfactory means for producing and focusing a high-intensity beam over a suilicient range of beam voltages to insure the necessary photographic sensitivity. The solution of this problem constitutes one of the major advantages of the invention.

Other objects and advantages of the invention will appear from a consideration of the following detailed description in conjunction with the accompanying drawings illustrating a `preferred embodiment of the invention. In these drawings: 55

Figure 1 is a side elevational view of an assembled instrument constructed in accordance with the invention;

Fig. 2 is a-front elevational view of the instrument shown in Fig. 1;

Fig. 3 is an Yenlarged fragmentary vertical sectional view taken on the line 3 3 of Fig. 2;

Fig. 4 is a still further enlarged fragmentary vertical sectional View taken on the line 4 4 of Fig. 3;

Fig. 5 is a horizontal sectional view taken on the line 5 5 of Fig. 4;

Fig. 6 is an enlarged horizontal sectional view taken on the line 6 6 of Fig. 3;

Fig. 7 is an enlarged fragmentary vertical sectional view taken on the line 1 1 of Fig. 2;

F'ig. 8 is an enlarged fragmentary vertical sectional View taken on the line 8 6 of Fig. 2;

Fig. 9 is a fragmentary vertical sectional view taken on the line 9 9 of Fig. 8;

Fig. 10 is a view, partly in side elevation and partly in central vertical section, of a particular type of electron tube that is preferably utilized in automatically controlling certain circuits for imparting a timing motion to a cathode ray or beam in an oscillograph constructed in accordance with the present invention;

Fig. 11 is a horizontalsectional view taken on the line II--H of 10;

Fig. 12 is a diagrammatic view showing certain parts of the instrument considerably enlarged in vertical section on the same line as that on which Fig. 4 is taken and illustrating the nature of an electrostatic field established between certain of the parts for a purpose hereinafter specified;

Fig. 13 is a diagrammatic representation'of certain` electrical apparatus and circuits, whereby an oscillograph constructed in accordance with the invention may be arranged andconnectedto be brought into operation automatically upon the occurrence of transient phenomena which it is desired to record;

Fig. 14 is a diagrammatic representation of a modified system of circuit connections for the same purpose as the system shown in Fig. 13;

Fig. 15 is a diagrammatic representation of' the phase relations of the various characteristics of the circuits shown in Figs. 13 and 14'; and

Fig. 16 is a diagrammatic representation of certain electrical apparatus and circuits for imparting a timing motion to a cathode ray or beam in an oscillograph constructed in accordance with the present invention, in a preferred manner.

The general elements of construction of the preferred embodiment of the invention are best shown in Figs. l and 2 of the drawings, in which it may be seen that a base plate 2l supports a horizontally extending cylindrical chamber 22. From the upper portion of the chamber 22 a tapered casing portion 23 extendsrupwardly to support a vertically extending casing portion 24, theexterior of which is shown as being octagonal in cross section. To the upper extremity of the casing portion 24, a cylindrical casing portion 25 of insulating material is secured by means of a sleeve nut- 26, and to thi;` -upper extremity of this casing portion 25 another cylindrical casing portion l21 is, in turn, secured by means ci a sleeve nut 28. The upper extremity of this casing portion 21 is closed by an insulating cap member 29 that is secured in position by a sleeve nut 30. The casing portions 24 and 21 are of metal and are adapted to have relatively high potential conductors connected thereto; and for this reason it is desirable to surround the saine by protective Ation vof the instrument and for this purpose a connection 36 is provided to extend to a suitable vacuum pump. The connection 36 is connected to the casing portions 22 and 23 through a drying chamber 31 and two pipe or conduit sections 36 and 39. One end of the drying chamber 31 is provided with a removable cap 40 to permit the insertion of a container of drying material, such as a suitable hygroscopic chemical or the like, and the opposite end of this chamber is provided with a valve 4| for controlling the connection of the instrument casing to the vacuum pump through the connection 36. 'I'he latter connection preferably. includes a second valve 42 for connecting the-'interior of the instrument casing to the atmosphere in order to break the vacuum within saidcasing when desired.

One end of the cylindricalportion 22 of the casing is provided with a hinged door 43 adapted to be tightly sealed by a suitable gasket or otherwise and to be opened by means of a handle 44. Since this door is held very tightly closed by the external atmospheric pressure when the interior of the casing is evacuated, it is also desirable to provide a releasing screw 45, which extends through a screw threaded hole in a projecting portion of the end wall of the casing portion 22 and abuts against the inner surface of the door 43 near the periphery thereof. A pin 46 extends through a hole in the head of the screw 45, in order that this screw maybe turned manually to effect a slight opening of the door 43 when the vacuum within the casing has been broken. When the door 43 is ius moved a slight distance it may be readily opened by means of the handle 44.

A tubular -member 41 is secured to one side of the tapered casing portion 23 and extends angularly therefrom in such direction that a viewing screen within the cylindrical casing portion 22 may be observed through a suitable Window in the outer extremity of said tubular member. The structural details of such viewing screen and observing window will appear hereinafter. It may be noted here, however, that a cover 41a prevents light from entering the casing through said window when the latter is not in use'.

Referring now to Figs. 3, 4, 5, and 6, it will be seen thai the uppermost cylindrical casing portion 2, which is preferably of brass or other suitable metal, is externally screw threaded near its upperl extremity to receive the internally screw threaded portion of the4 flanged sleeve Sil. The upper portion of this sleeve comprises an inwardly extending flanged portion' 30a, which extends over a shoulder portion 29a of the insulating cap member 29. The bottom surface of the cap member 23 is provided with an annular groove fitting over a reduced diameter portion 21a of the metallic casing portion 21 at the upper extremity thereof. An annular washer or gasket 48 is disposed Within the annular groove in the bottom of the cap member 29 and is forced rmly against the top surface of the reduced diameter portion 21a by the firm application of the flanged sleeve 36 to the threaded portion of the member 21. The washer or gasket 48 is preferably made A rubber gasket 50 is placed beneath the plug member 49 and both the plug member and the gasket are perforated to accommodate two conducting rods which extend downwardly through the cap member 29 as well as upwardly through the plug member 49, the cap member 29 being similarly perforated for this purpose.

The rods 5I are provided with integral collar portions 5|a about midway of their length, and these collar portions are disposed within counterbores in the cap member 29. The under faces of the collar portions 5Ia are tapered to produce a frusto-conical surface corresponding to the angle of inclination of the bottoms of the counterbores in the cap member 29 and rubber gaskets 52 are disposed between the bottoms of the collar portions 5la and the bottom surfacesof these counterbores.

The plug member 49, the gasket 50, the conductors 5I, and the gaskets 52 are maintained in assembled relation, as shown, by machine screws 53 extending through suitable holes inthe plug member 49 and enteringsuitable threaded openings in the plug member 29. These screws are screwed tightly into position to hold the parts in rm engagement with each other, whereby the rubber gaskets form an air-tight seal for the interior of the casing.

The lower extremities of the conductors `5| have connecting sleeves 54 suitably secured thereto, as by set-screws 55, and exible conducting leads 56 are respectively soldered to or otherwise suitably electrically connected with the sleeves 54.

The lower extremities of the flexible leads 56 are similarly connected to two connecting sleeves 51 which, in turn, are respectively secured by setscrews 58 to conductor rods 59 and 60. The rod 60-is soldered or otherwise suitably connected to a metallic locking sleeve 6l that is provided with external screw threads, as is also a metallic sleeve 62, to cooperate` with corresponding internal screw threads in another metallic sleeve 63. The sleeve 63 is suitably secured within an insulating bushing 64 by means of nuts 65 and 66 respectively engaging external screw threads at the upper and lower extremities of said sleeve, and the sleeve 62 is adapted to be adjusted to any desired vertical position with respect to the sleeve 63 by reason of its screw-threaded engagement therewith, and to be locked in the desired position by means of the locking sleeve 6I, which thus acts be adjusted by varying the positions of the nuts 65 and 66 on the screw-threaded portions of said sleeve. Y

The insulating bushing 64,111 turn, is supported by a tubular metallic sleeve member 61 having a free sli ing t with respect to the interior of the` tubular casing portion 21. l'Ihe bushing 64 ts snugly within the bore of thesleeve 61 and its lower extremity rests upon a shoulderformed by an inwardly extending ange or bottom portion 61a ofthe sleeve 61. An annular securing nut 68 surrounds the reduced-diameter portion 64a at the top of the bushing 64 and is provided with external screw threads cooperating with internal screw threads in the upper portion of theA bore of the sleeve 61. By screwing the nut 68 rmly into the upper extremity of the sleeve 61, the bottom of this nut is caused to force the bushing 64 firmly down against the inwardly extending shoulder portion 61a of the sleeveA 61 and the bushing 64 is thus firmly secured within the metallic sleeve 61.

The outer surface of the metallic sleeve 61 is n upon the top of a substantially bell-shaped but open-top metallic member 69 as a support. The member 69 comprises a perforated integral collar portion 69a that is externally screw-threaded for the `purpose of securing the same within the lower extremity of the casing portion 21, which is internally screw-threaded to receive the same.l

The perforations in the collar portion 69a of the member 69 are provided for the same purpose as the grooves 61h in the outer surface of the metallicisleeve 61, that is, to permit the free passage of gases between the vvarious portions of the interior of the casing. The bottom portion 61a of the sleeve 61 is likewise perforated, as at 61e, to connect the open space within the-sleeve with the remainder of the casing.

The bottom of the sleeve 61 is closed by a plate or disc 10 having a tapered central aperture10a therein for a purpose hereinafter specied. While the bottom wall of the casing 61 may, if desired, be integrally formed and perforated at 61e and 1lla,lit is preferable that provision be made for accommodating removable plates or discs 10 as shown, in order that such' plates or discs having apertures 10a of different sizes or formations may be interchangeably utilized to obtain the best possible results in operation the instrument.

An insulating bushing 1l is secured within the bore of the metallic sleeve 62 by means of an cxternally screw threaded annular nut 12cooperating with corresponding screw threads on the inside of the bore of the sleeve 62. The bottom of the bushing 1| is beveled to bear against a similarly beveled inwardly extending flange portion 62a of the sleeve 62 whereby the bottom of the bushing 1I is supported. The bushing 1I supports the conductor rod 59 which extends in snugly fitting relation through the bore of said bushing and-which is provided with an integral collar portion 59abearing against the bottom of said bushing.

The portion of the conductor 59 immediately above the upper surface of -the bushing .1I is screw-threaded to cooperate with an internally screw-threaded nut 13 which extends within the bore of the annular securing nut 12 and in spaced relation thereto.v The bottom of the securing nut 13 thus bears against the top of the bushing 1| and when this nut is tightened it holds the conductor rod 59 securely within said bushing and in insulated relation to the metallic sleeves 6|, 62 and 63.

A ribbon-type lament 14 is supported within the metallic sleeve 63 and near Athe lower extremity thereof by two lead wires 15- and 16 to which the opposite extremities of said lament are respectively connected and which, in turn, are respectively connected to the metallic sleeve 62 and the conductor rod 59. The lead wires 15 and 16 are preferably supported with respect to each other by a glass bead 11 near the lower extremity of said lead wires.

yse

It will be seen that the' ends of the filament 14 are respectively connected, through the several vmembers described, with the two conductor rods extending upwardly through thel cap member 29 of the casing, and that the end of the filament which is connected to the lead wire is electrically connected to the metallic sleeve 63 through the sleeve 62. It is preferable in some cases to have both4 of the filament leads insulated from the sleeve 63, in which case it will be readily understood that the conductor 60, instead of being connected to the sleeve 62 as shown, will extend downwardly through the insulating bushing 1| in a manner similar to that in which the conductor 59 so extends, as herein shown and described.

The bottom of the sleeve 63 is internally screwthreaded to receive a similarly screw-threaded cap member 18 having a central aperture 18a therein in alignment with the aperture 16a in the plate or disc 10 closing the bottom of the sleeve 61. These two apertures are also in alignment with the filament 14 (which, however, is wider than said apertures), and are provided to permit the passage of electrons emitted from said filament in the desired downward direction. This filament is preferably provided with an oxide coating to facilitate such electron emission in a manner well known in the art. This oxide coating `is preferably applied to the lament on the bottom surface only thereof, since it is desired that electrons be emitted only in .a downward direction. It is for the purpose of preventing the emission of electrons in other directions that the filament is enclosed by the metallic sleeve 63 and the cap closure 18, which constitute an effective filament shield.

The lower portion of the sleeve 63 is perforated, as at 63a, to facilitate the complete evacuation of the open space within said sleeve, thus insuring the complete removal of any gases that may be given off by the lament 14 when it is heated. Since the insulating bushing 64 extends downwardly around the lower extremity of the sleeve 63 for a substantial distance below the level of the perforations 63a. the emission of electrons through these perforations is substantially prevented It will be noted that the filament 14, its shield 63 and the plate or disc 10 constituting the top of the negative electrode 69 are" assembled into a compact unit carried by the sleeve B1, which unit is readily removable from.` and replaceable in the casing portion 21 and Vwhich simply rests tachable when it is desired to remove or replace the unit. 'I'his unit is designated as the "electron gun, because it comprises the means for establishing the cathode ray or electron stream and for initiallyI focusing and accelerating the same. This initial focusing and accelerating effect can be regulated as desired by adjusting the spacing between the filament 14 and the plate I8 and between the plate 18 and the plate 10, or the bottom of the member 61..

The lower extremity of the casing portion 21 comprises an integral collar portion 21h that is adapted to be engaged by an inwardly extending flange portion 28a of the securing sleeve 28. An annular groove is provided in the bottom edge of the casing portion 21 and a reduced diameter portion a of the insulating casing portion 25 extends in snugly fitting relation into this groove and abuts against a rubber gasket or washer 19 to form an air-tight connection between the casing portions 25 and 21. These two casing portions are securely held in their respective positions by the securing sleeve 28,' which is internally screw-threaded to cooperate with corresponding external screw-threads at the upper extremity of the casing portion 25. As will hereinafter appear, the bell-shaped ,metallic member 69 constitutes anegative electrode for the establishment of an electrostatic field in the path of travel of the electrons emitted from the filament 14. A cooperating positive electrode is provided in the form of a hollow cylindrical member 80, the upper extremity of which is of substantially smaller diameter than the internal diameter -of the member 69. The upper extremity of the positive electrode 80 is closed by a metallic cap member 8| having an annular protruding portion 8|a on the bottom thereof fitting snugly within the bore of the electrode`80. The cap member 8| has a central aperture 8| b therethrough in Vertical alignment with the apertures 'lia and 18a and the filament 14 to accommodate the electron jet or beam emitted downwardly from the filament 14. The aperture SIb is .enlarged conically in a downward direction, as shown, thus forming a sharp edge at the top of the member 8| and preventing reflection of electrons from the walls of said aperture.

Referring now to Fig. 7, it will be seen that the positive electrode 80 is supported by a tubulax member 82 into which a reduced-diameter portion 80a at the lower extremity of said electrode 80 snugly fits, the shoulder formed by the upper extremity of this reduced diameter portion resting upon the top of the tubular member 82. The member 82 is slidably tted within a tubular metallic casing portion 83 that is suitably secured to the upper extremity of the metallic casing portion 24, as by soldering, brazing, or the like. 'I'he outer surface of the tubular member 82 is provided with a plurality of longitudinal slots or grooves 82a in a similar manner and for the same purpose that the grooves 611) are provided in the outer surface of the metallic sleeve member 61 as heretofore described.

A rack 84 is provided on one side of one of the grooves 82a and is adapted to cooperate with a pinion 85 secured to or forming an integral part of a shaft 86 extending outwardly through an aperture in the tubular casing portion 83. A sealing gland or joint is provided around the shaft 86' to maintain an air-tight seal around said shaft. This gland or joint comprises a substantially cylindrical hollow casing portion 81 having its inner extremity tted and brazed or welded into a counterbore in the outer surface of the casing portion 83, which counterbore is coaxial with the aperture in said casing portion through which the shaft 86 extends. The bore ofA the member 81 is restricted at the inner extremity of said member to a diameter similar to that of the aperture in the member 83which is just large enough to permit the shaft 86 to extend therethrough in freely rotatable relation. A mass of packing material 81a is disposed Within the gland casing 81 around the shaft 86 and is held inplace between the opposed concave surfaces of the inner end portion of the member 81 and a packing disc or washer 81h. The inside of the bore of the memberl 81 is screw-threaded to receive an externally threaded plug member 8,1c that is centrally apertured to surround the shaft -86 in closely fitting but free running relation and that is also provided with apertures 81d for the reception of a suitable Wrench or other tool for forcing the disc or washer 81h against the packing material 81a. A bushing member 81e that is also centrally apertured to receive the shaft 86 in closely tting but free running relation comprises an externally screw-threaded reduced-diameter portion, that is screwed into the outer extremity of the gland casing 81 to provide a journal for the outer portion of the shaft 86, the casing 81 being of such length that when theparts are assembled a substantial amount of space remains between the members 81e and 81e and the casing 81 is provided with an aperture 81j on its upper side to permit this space to be filled with grease as indicated at 81g. In this manner the oscillograph casing is made completely air-tight around the shaft 86, the grease 81g v supplementing the packing 81a to form a perfeci: seal. This type of vacuum seal is believed to be new and is claimed as a part of the invention disclosed herein. n

The outer extremity of the shaft 86 is preferably provided with a knurled knob 88 which may be turn-ed manually to adjust the vertical position of the slidable tubular member 82 and the positive electrode 80 that is carried thereby. Such manipulation of the knob 88 results in any desired change of the vertical position of the positive electrode 80 with respect to the negative electrode 69, this adjustment being provided for a purpose hereinafter explained.

The insulating casing portion is secured in xed relation to the tubular casing portion 83 by the securing sleeve 26, which comprises an in- `wardly extending flange portion 26a engaging the shoulder formed by an integral collar portion 25h near the lower extremity of the member 25. The lower portion of. the securing sleeve 26 is internally screw-threaded to cooperate with corresponding external screw threads on the upper portion of the member 83 whereby the sleeve 26 maybe screwed down to forcethe casing portion 25 downwardly into tight engagement with the.

`casing portion 83. For the purpose of providing an air-tight connection at this point, the member 83 is provided on its top surface with an annular groove into which a reduced-diameter portion 25e at the bottom of the casing portion 25 extends in snugly fitting relation and is forced against a rubber gasket or washer 89 in a manner similar to that described with respect to the air-tight joint between the cap member 29 and the casing portion 21 and between the top of the casing por.-

tion 25 and the bottom of the casing portion 21.

'I'he lower portion of the member 83 is reduced in diameter to form a downwardly extending portion 83a spaced inwardly from the inner Wall of the casing portion 24 and having an annular groove 83h formed in its inner surface. A plurality of perforations 83e extend through the downwardly extending portion 83a of the member 83 to connect the interior` of the casing portion 24 with the interior ofthe casing portion 25 through the annular groove 83h and the longitudinal grooves 82a in the outer surface of the member The provision of these various grooves and perforations is also for the purpose of facilitating the evacuation of the entire open space within theseveral portions of the casing, as in the case of the several grooves and perforations heretofore described.

The backs of two pairs of metallic plates 90 and 9| are secured, within the casing portion 24, to the inner extremities of rods 92 and 93 respectively, the two rods supporting each pair of plates having a common axis perpendicular to the axis of the rods supportingthe other pair of plates. Each of the pairs of supporting rods 92 and 93 extends outwardly through sealing glands 94 and 95, respectively, which are packed and sealed with grease as in the case of the gland 81. The inner portions of the glands 94 and 95 are preferably of brass or'other suitable metal suitably iitted and secured in'apertures in the walls of the metallic casing portion 24, as by soldering, brazing, or the like.

The glands 94 and 95 are constructed to 'insulate the rods 92 and 93 from the oscillograph casing, as well as to provide a perfectly air-tight seal therearound, and forthis purpose they comprise outwardlyextending portions 94a and 95a, respectively, of suitable molded insulating material, or the like (see also Figs. 1 and 2), Withinv which adjusting nuts 96 and 91, respectively, are disposed to be freely rotatable but xed against axial sliding movement. The adjusting nuts 96 and 91 are internally screw-threaded to cooperate with external screw threads 92a and 93a on the outer portions of the rods 92 and 93, respectively, whereby the spacing between each of the pairs of plates 90 and 9| may be varied by turningthe nuts 96 and 91. In order to prevent rotation of the rods 92 and 93 while the nuts 96 and 91 are being adjusted, the outer extremities of angularly bent wires 98 and 99 are secured to the outer extremities of the rods 92 and 93, respectively, and the inner extremities'of these wires are secured to pins |00 and |0| carried by the outwardly extending insulating portions 94a and 95a, respectively, of the sealing and insulating glands 94 and 95.

It will appear hereinafter that the cathode ray or beam emitted from the filament 14 and accelerated downwardly through the instrument duced diameter portion 83a of the member 83.v This diaphragm |02 is supported upon an annular inwardly extending shoulder portion 83d at the bottom of the reduced-diameter portion 83a and cooperates therewith to limit the downward movement of the vertically slidable member 82, which abuts against the upper surface of the diaphragm |02 when it is in its lowermost position.

The diaphragm |02 is preferably composed of sheet nickel and the aperture |02a therein is of such size as to permit the passage of the entire main portion of the cathode ray or beam while the portions oi the diaphragm surrounding the aperture |02a intercept and cut off any stray electron emission which may be caused by a positive ion bombardment of the negative electrode 69 or other causes. Y

An externally screw-threaded annular member |03 is disposed at an intermediate point within the casing portion 24 between the two pairs of dei'lecting plates 90 and 9| and is held in position by cooperating screw threads provided in the inner surface of the casing portion 24, this casing portion being counter-bored, as at 24a, to permit the insertion of the member |03 from the bottom of said casing portion. This member is provided for the purpose of supporting a metal plate (not shown) between the two sets of deflecting plates 90 and 9| where it is found necessary to utilize such a plate to prevent voltages from being induced on Aone pair of platesl from the other. The reason for not showing this plate and describing the same more fully is that it is not required for normal operation of the instrument, although the latter, as will be seen, has been designed to accommodate such extraordinary requirements.

The lower extremity of the casing portion 24 extends into an annular groove in the upper surface of a metallic collar member |04 and is suitably secured thereto by soldering, brazing, or the like. The lower surface of the member |04 comprises a downwardly extending annular portion |04a which extends in snugly fitting relation into an annular groove in the upper surface of a member |05, which constitutes the supporting base of the upper parts of the instrument. A rubber sealing gasket |00 is placed in the bottom of the groove in the upper surface of the member |05 and the bottom of the annular projecting portion |04@ of the member |04 is forced against this gasket by a securing nut |01 having an inwardly extending flange portion |01a at its upper extremity engaging the shoulder formed by the top of the collar member |04. The securing nut |01 is internally screw-threaded to cooperate with corresponding external Screw threads on the member |05 and the outer surface of the member |01 is suitably knurled, as at lillb, whereby'it may be firmly screwed down onto the member |05 to make an air-tight connection between the members |04 and |05, as in the case of the similar air-tight connections heretofore described.

The lower extremity ofthe member |05 comprises anintegral outwardly extending annular flange portion |0511 upon which the bottom plate 33 is adapted to rest, this plate being centrally plates 3| which, in turn, support the intermediate Y plate 34 that is centrally apertured to pass over the upper vextremity of the casing portion 24. The bottom plate 33 also has secured thereto,

as by securing nuts |09,` the lower extremitiesof the rods 32, to the upper extremities of which the top insulating plate 35 issecured, as by nuts H0.

Each of the rods 32 is formed in two parts suitably joined together atthe level of the intermediate plate 34. The lower portion 32a of each of these rods, extending between the plates 33 `and 34, is preferably of metal of square cross receive the upper extremity of the tapered casing portion 23 which is also of metal and is permanently secured to the member |05 in air-tight relation by soldering or brazing, as indica-ted at Referring now to Figs. 8 and 9, it will be seen that the lower extremity o`f the tapered casing portion-23 registers with an aperture in the top of the horizontally extending cylindrical casing portion 22 and is permanently and tightly `secured to said casing portion 22 by soldering or brazing. as indicated at H2.

The ends of the casing portion 22 are respectively supported by vertical end plates ||3 and l I4 which are suitably secured to the ends of said Casing portion by soldering or brazing to form perfectly air-tight joints. The end plate ||3 closes the left hand end of the casing 22, as

viewed in Fig. 8, and is aperturedl to receive the inner extremity of the pipe or conduit 38, the

other extremity of which connects with the interior of the drying chamber 31. The pipe or conduit 39 similarly connects the drying chamber 31 with the casing portion 23, it being understood that both of the pipes or conduits 38 and 39 are brazed or soldered to the members to which they are connected at their respective extremities to forrn air-tight connections. The provision of the two pipes or conduits 38 and 39 insures complete and rapid evacuation of all parts of the casing without causing the air or other gases therefrom to encounter any unnecessary obstructions.

A tray or open container ||5 is disposed .within the drying chamber 31 and is adapted to hold a quantity of phosphorous pentoxide or other hygroscopic material ||6 to prevent the passage of any moisture from the interior of the instrument (particularly from photographic lms) into the pumping apparatus, where deleterious results would be caused thereby. The interior of the drying chamber 31 is connected through the valve 4|, -as best shown in Fig. 9L with the connection 36 which extends to the vacuum pump (not shown), as previously stated. This valve is sealed to' prevent any leakage of air into the instrument at this point, by means of grease supplied by a grease cup 31a to an interior annular groove 31h near the outer extremity of the member 31 surrounding the body portion of the valve 4|.

A sealing and insulatin'gfgland ||1 is also connected to the end plate ||3 for the purpose of permitting electrical conductors ||8 to be extended from the exterior of the casing into the interior thereof in electrically insulated and airtight relation thereto. These conductors may be utilized for making connections to vacuum indicating lamps or devices and other circuits which it may be found desirable to utilize within the casing of the instrument, particularly in the portion 22 thereof. One of the conductors ||8 is shown as being connected to a contact member ||9 bearing upon .the periphery of a metallic disc having an insert |2| of insulating material at a predetermined point therein. 'I'hese parts may be utilized in connection with a nlmw'lnding mechanism, as will be more fully described hereinafter.

The end plate ||4 of the chamber portion 22 is apertured to permit the insertion and removal of the above mentioned nlm-winding mechanism, and this aperture is adapted to be closed and tightly sealed by the hinged door 43, as previously described. The nlm-winding and carrying mech' anlsm is constructed as a removable unit adapted to be supported by a frame |22, which is constituted by a piece of sheet metal forming a portion of a cylinder and apertured substantially in register with the bottom of the casing portion 22. The frame member |22 is located at the upper portion of the nlm-winding and supporting mechanism and is adapted to nt within the interior of the horizontally extending cylindrical casing portion 22 and to be supported upon rabbetted or grooved longitudinal rods |23 secured to the inner surface of this portion of the casing. With this manner of support it will be seen that the nlm mechanism may be slid into the casing portion 22 through the opening in the end wall ||4 when the door 45 kis open and that this mechanism' will be accurately held in the desired position forthe purpose of obtaining photographic records of the movements of the cathode ray, as will appear hereinafter.

Suspended from the supporting frame |22 are two end plates |24 and |25 between which a plurality of supporting rods |26 extend. The respective extremities of the rods |26 are secured to the end plates |24 and |25 by screws |21, or other suitable means, and in this manner a rigid frame-work for the operative parts of the nlm mechanism is eventuated. Film-winding rolls or spools |28 and |29 are provided with suitable pintles journaled in the end plates |24 and and a photographic nlm 30 is adapted to be wound from one of these rolls or spools onto the other in the operation of the instrument. 'Ihe nlm extends between the two rolls or spools |28 and |29 over two idler rolls |3| and |32, which are also journaled in the end plates |24 and |25. I

Between the idler rolls 3| and |32 a horizontally extending plate or table |33 is disposed for supporting an intermediate portion of the nlm in register with the aperture through the top of the casing portion 22 and with thel bottom of the casing portion 23. This plate or table |33 is rigidly secured at its opposite extremities to the end plates |24 and |25, and thus forms a solid support for the portion of the nlm |30 upon which the photographic records are made. Beneath the plate or table |33 a nxed tray |34 is disposed, this tray also being rigidly secured at its opposite extremities to the end plates |24 and |25. This tray is adapted to support a removable tray |35 carrying a quantity of phosphorous pentoxide or other hygroscopic material |36 for absorbing any moisture which remains in the nlm 30 when the same is placed in the casing portion 22. 4

A resilient member |31 is supported by two of the rods |26 near the bottom of the end plates |24 and |25 and extends inwardly and upwardly past the nlm-winding rolls or spools |28 and |29. The upwardly extending portions of the member |31 are comb-like to form a plurality of resilient prongs or nngers |3'la which bear firmly against the nlm 30 as it is wound upon or unwound from the rolls or spools |28 and |29. The pressure exerted upon the nlm |30 by these resilient prongs |3`|a maintains the desired degree of tautness in the portion of the nlm between the two rolls or spools |28 and |29.4 A handle member |138 is suitably secured to the end 'plate 25 to facilitate insertion and removal of the film mechanism into and out of the chamber 22. The right-hand extremity-of the nlm-winding roll or spool |29 is pivotally supported on a pintle |30 which may be maintained in its operative position as illustrated by any suitable and well known means, and which may be retracted by means of a knurled knob |39a to permit removal and replacement of the spool |29. The right-hand extremity of the spool |28 is similarly supported by a corresponding retractible pintle (not shown). The left-hand extremity of the roll or spool |28 is adapted to be engaged by suitable turning prongs or fingers (not shown) connected to a knurled knob |40 (Fig. l), the spindle of Whicl'.` extends through the end wall ||3 through an air-tight sealing gland |4I, to permit winding of the nlm from the roll or spool |29 onto the roll or spool |28 from the outside of the casing of the instrument while the inside of said casing is evacuated to place the instrument in condition for operation.

By means of this mechanism, it will be understood that successive portions of the film |30 may be brought into register with the aperture in the top of the casing portion or nlm chamber 22, through which the cathode ray or beam enters said chamber. This operation may be performed without breaking the vacuum within the casing of the instrument, and thus a considerable number of photographic records may be made in a short time without extended intermediate delays, which would be occasioned if it were necessary to open the casing each time establish the vacuum after each nlm change.

The purpose of providing the contact disc |20 and cooperating contact nnger ||9 will now appear. The disc v |20 is carried by and secured to the left-hand extremity or pintle of the idler rotates with said idler roll. This roll is moved in unison with the movement of the nlm |30 by reason of the frictional engagement between the nlm and roll, since the 'intermediate portion of the nlm between the two winding rolls |28 and |29 is dalways maintained in a taut condition, as previously described. Therefore, when the nlm is wound from the roll 20 onto the roll |28 by manipulation of the knurled knob |40, the contact disc |20 is rotated to a degree that is exactly proportional to the distance through which any given point of the nlm moves. 'I'he circumference of the roll |32 is such that one complete revolution thereof corresponds to a movement of the film- |30 through a distance `the nlm was to be changed, and therefore to re, l

`roll |32, as shown in Fig. 8, whereby this disc equal to the length of lm utilized at each exposure thereof.

The initial exposure setting of the film is made with the contact iinger H9 in contact with the insulating insert |2| in the disc |20. When the film is moved toward the position which it is to -occupy during its next exposure, the contact finger H9 contacts with the conducting portions of the disc to establish an electrical circuit between one of the insulated conductors H8 and the metallic frame of the instrument. This condition may be indicated by connecting the said one of the conductors H8 and the frame of the instrument in series with a lamp or other indicating device, which may be conveniently located for that purpose, and which is not shown herein in order to avoid unnecessary complication of the drawings. When the desired movement of the nlm has been effected, the contact finger H9 again engages the insulating insert |2| in the disc |20 and interrupts the indicating circuit, it being understood that the contact finger H9 is otherwise suitably insulated from the frame-work or casing of the instrument. Upon extinguishment ofthe lamp or .corresponding indication of any other indicating device that may be utilized, the operator is iniormed that A, the film has beenl moved through the desired distance and that a fresh portion thereof is ready for exposure. It is also contemplated that the contact mechanism comprising the finger I9 and the disc |20 having the insulating insert |2| therein may be utilized to eiiect automatic operation of the film by an velectric motor or other suitable means in response to any desired condition indicating that a record has been made on the exposed portion of the film and that a fresh portion of the film should be brought into the field of exposure. The essential element of this feature of the invention, however, is ln associating the indicating mechanism comprising the disc |20 with an idler roll, such as the roll |32, that is rotated through a predetermined degree for any given movement of the film |30, while the degree of rotative movement of the winding rolls |28 and |29 is variable depending upon their eiiective circumferences, that is, depending upon the amount ofv film which has been Wound from one, of these rolls onto the other.

For the purpose of permitting visual inspection of the movements of the cathode ray or beam under the inuence of the phenomena being observed, a phosphorescent or fluorescent screen |42 is hinged about a horizontal axis at |43 to a fixed portion of the frame |22 of the iilm mechanism. This screen is adapted to' be rotated about the axis |43 between the full line and dotted line positions indicated in Fig. 9. In the dotted line position, as shown in this figure, the, screen is entirely out of the path of the cathode ray or beam, which therefore imping'es on the film |30 and is photographicall; recorded thereon. When the screen |42 occupies the position indicated in full lines in Figs. 8 and 9, it is horzontally disposed above the exposed portion of the film 30 in the path of the cathode ray or beam, and the upper surface thereof may be viewed through a glass window |44 that is provided near the outer extremityof the tubular member 41, as indicated in Fig. 8. The window |44 is tightly sealed in the outer end of the tubular member |41 by means of suitable gaskets |45 and a flanged securing sleeve |46 that is internally screw-threaded to cooperate with core responding external sci-ev1 threads atthe outer ture therein by means of soldering or brazing, *to form an air-tight connection at this point.

It will be seen from an examination of Fig. 8 that the viewing screen |42 may be clearly viewed through the window |44 when said screen is in its operative position as shown. AThe screen or the mounting plate therefor also serves in this 4I position as a light-proof shutter to protect the lm |30 from exposure to light entering the casing through the window' |44. It will be understood, of course, that the cap or cover 41a previously mentioned with reference to Figs. l and 2 is used to cover the window |44 when the movements of the cathode ray or beam are being recorded on the film |30 instead of being viewed on the screen |42. This cap or cover prevents the entrance of light into the film chamber through the window |44, which light might affect the sensitized lm |30. The provision of such a cap may not be necesary, however, where the window |44 is composed of colored glass which will not admit any light that will affect the film |30, l

but which will permit the observation of the path of movement of the cathode ray or beam as indicated on the screen |42.

The screen 42 is adapted to be actuated between its operative and inoperative positions by means of a pin |48 extending through an airtight sealing gland |49 in the end wall H3 of the film chamber 22, as shown in Fig. l. The outer extremity of the pin |48 is provided with an operating handle |50, and the inner extremity of this pin is adapted to engage the axial portion |43 of the screen |42 in a suitable operative manner. Thus, the instrument may be adapted either for visual observation or for photographic recording of the movements of the cathode ray or beam by simplymanipulating the handle |50 on the outside of the casing. It will be understood that the screen |42 is so mounted that it will remain in either of its two positions when it has been actuated into such position by the manipulation of the handle |50.

The enlarged view of Fig. l2 diagrammatically indicates the manner in which the cathode ray or beam is emitted from the filament 14 and electrostatically focused. In this figure the lines |5| indicate the electron emission from the filament 14, the electrons thus emitted passing through the relatively large central aperture 18a in the member 18 of the filament shield. An electrostatic field indicated by the lines |52 is created between the member 18 and the member 10 which constitutes'the top of the negative electrode -69. This electrostatic field |52 is created by applying a suitable potential diierence between the iilament shield 63 and the negative electrode 69. This potential difference may be of any desired magnitude, but it has been found thata potential difference of between and 2,000 volts produces the most satisfactory results. The negative electrode 69 is positively energized with respect to the filament shield 83 by means of this potential difference, the member 69 being designated as the negative electrode because it is negatively energized with respect to the positive electrode 30, as will hereinafter appear.

The electrostatic eld |52 exerts a focusing and accelerating eiect upon the cathode ray or beam between the filament shield and the top of the negative electrode 69 and'the ray or beam is thus caused to be projected downwardly through the central aperture a, where it is brought to a focus, into the interior of the bellshaped member 69. The stray or unfocused electrons which pass through the aperture 18a in e the bottom of the lament shield are intercepted by the member 10, the aperture 10a therein being of such size as to permit only a relatively thin pencil of focused rays to pass therethrough.

The negative electrode 69 and the positive electrode |30 are respectively connected to the negative and positive sides of a suitable source of potential difference to create an electrostatic field between these members, as indicated by the lines |53. The magnitude of this potential difference may be varied between relatively wide limits, it having been found in actual practice that potentials varying anywhere between 300 and 20,000 volts produce satisfactory results. -It will be understood, of course, that the invention is .notlimited to the use of any particular potential difference or range of `potential diierence as applied to'these or any other portions of the instrument, the figures given being stated merely by way of examples.

Due to the telescoped relation of the electrodes 69 and 80, the electrostatic `eld |53 is caused to converge downwardly toward the positive electrode 80, as indicated by the inclination or curvature of these lines in Fig. 12. 'The utilization of the electrodes 69 and 80 in the relation disclosed is an important feature of the invention because it has been found that a converging field of this character exerts a strong focusing effect upon the cathode ray or beam, which is diagrammatically indicated by the lines |54. The electrons in the beam |54 start to diverge as indicated after passing through the focus at the aperture 10a and they also exert a mutually repelling effect by reason of their similar negative charges. This repelling effect would normally cause the beam to be substantially dispersed in the relatively long path of travel ofthe electrons. However, by utilizing the converging electrostatic field |53, as disclosed, this dispersive eiect is entirely overcome, and the cathodebeam |54 is accurately focused upon the film |30 or the viewing screen |42. 'I'his effect is obtained because the radial component of the field |53 imparts to the electrons constituting the cathode ray or beam a component of velocity toward the center of the beam, which radial component of velocity counteracts the dispersive momentum of the electrons caused by their mutual repelling forces during the entire length of the beam.

'I'he extent of the focusing eiectrequired under diierent operating'conditions may. vary considerably, and it is for this reason that the positiveV electrode is provided with adjusting means operable bythe knurled knob 88, as shown in Fig. 7 and previously described. By adjusting the knob 88 the positive electrode 80 may be raised or lowered a substantial distance to eieot the exact degree of convergence of the electrostatic iield |53 which will eiect the necessary focusing efect'upon the beam |54. This will be apparentv from a consideration of thestructure disclosed, since a raising ofthe positive electrode 80 will obviouslyv eiect such a change in the inpositive electrode 80 is such as to give a widerange of variation by this means alone', whereby it is not ordinarily necessary to change the magnitude of the voltage applied to the electrodes 18 and 10 for ordinary variations in the conditions under which the instrument is operated.

It will be also understood that the electrostatic field |53 exerts an accelerating eiect upon the cathode ray or beam |54 whereby the desired velocity of this beam is obtained. The magnitude of this accelerating effect may be readily varied by varying the potential difference that is applied between the electrodes 6a. and 80, so that any desired velocity of the beam may be obtained for any given operative conditions. Thus, the spacing of the electrodes 59 and 80 and the magnitude of the potential difference that is utilized therebetween may be adjusted so that both the focusing e'iect and accelerating eiect of the field able telescoped relation is believed to be entirely new and is broadly claimed herein, since this method may be utilized wherever a cathode ray or beam is to be focused for any purpose, such as in a television system or elsewhere.

. The beam |54, after passing through the electrostatic field |53` between the electrodes 69 and 80, passes through the central aperture 8|b in the cap member 8| at the top of the positive electrode 80, and thence continues downwardly through the interior of the electrode 80, which is made hollow for this purpose. The aperture 8|b is of sufcient size to permit the entire beam to pass therethrough and the inclination of the walls of 'said aperture'is such as to prevent the electrons from striking said walls, thereby eliminating undesirable conditions, particularly heating of the members 8| land 8|).

A s the'beam |54 continues along its downward path of travel within the positive electrode 80, any stray electrons which may be liberated from the beam are intercepted by the .walls of the member 8|) and are thus prevented from bombarding the interior of the insulating casing porl tion 25. This feature is of considerable importance because it has been heretofore considered necessary to construct such a casing portion of glass or similar material in order to withstand the high temperature caused by such stray electron bombardment. Such bombardment in instruments heretofore devised has been very lconsiderable because widely separated electrodes `field produced by closely spaced telescoped electrodes lsubstantially eliminates this condition in 'prevents ickering of the beam which might otherwise be caused by such charges.

When the beam |54 reaches the bottom of the space enclosed by the positive electrode 80 and the supporting sleeve 82 therefor, it passes through the aperture |02a in the plate |02, shown in Fig. 7. This plate intercepts the few stray electrons which may have been thrown oft from the main beam |54, but substantially all of the electrons in the beam are accurately maintained in focus by reason of the above-described action of the electrostatic field |53, and the entire beam thus focused passes freely through the -aperture |02a. The side walls of the aperture |02a are inclined as shown so that in case the beam is not properly centered through said aperture it will not be thrown out of focus by reason of the glancing or reection of electrons from these walls.

The cathode ray or beam then passes between the two pairs of. deecting plates 90 and 9|, and thence downwardly through the casing portion 23 to impinge upon the viewing screen |42 or the exposed portion of the film |30. An oscillating potential diierence of known frequency, or a varying potential difference of which the rate of change is known or can be determined, is connected between the two plates of one of the pairs 4010i plates 90 and 9| to cause the cathode ray or beam to be periodically oscillated or to produceI a time axisv or datum. Such a timing potential diierence may be derived from a vacuum tube circuit, which is advantageous because it is possible thereby to apply a straight-line timing motion automatically, or may be obtained in any other lsuitable manner well known in 'the art. 'I'he two plates of the other pair ofthe deiiecting plates 90 and 9| are connected to the circuit in which the phenomena to be observed or recorded obtain, and thus the cathode' ray or beam is deflected by such phenomena in adirection perpendicular vto that in which it is deflected by the timing potential difference thatv is connected to the other pair of plates. In this manner an indication on the screen |42 or a record on the film |30/is produced to indicate the exact nature of the phenomena under consideration.

'I'he instrument is also adapted for the use ol' electromagnetic means for defiecting the beam, which means are known in the art and generally comprise magnetic coils wound upon hollow cylindrical members of insulating material. Such a member may be secured, if desired, between the parts |04 and |05 of the instrument casing whereby the beam may be deflected magnetically instead of, or as well as, electrostatically. Such magnetic deecting means are not ordinarily required, but may be useful for laboratory work.

Thev focusing eiect oi.' the electrostatic field |53 is so adjusted that the dispersive tendency of the electrons in the cathode ray or beamV is counteracted to al sufiicient extent to concentrate the electrons throughout the entire path of their travel and bring them to an accurate Vductor |61 to the negative electrode 69. .conductor |61 is also adapted to connect the focus upon the screen |42 or film |30. Thus, the' beam produces a'well defined spot-of 'highifintensity on the screen or film whereby the'frnbv ments of the beam are accurately reprodu'bed thereon. In this connection it may be stated that the oxide coating on the bottom of the'ffila" substantially eliminate all light emission from said iilament in a downward direction through the several small apertures in the path of travel of the cathode ray or beam and therefore there is insuilicient light reaching the lm |30 from the filament 14 to have any effect upon said film except for very long exposures thereof.

The circuit diagram shown in Figs. 13 and 14 will now be described to illustrate an applica-l tion to which an instrument constructed in accordance with the present invention is particularly adapted.

In Fig.v 13 the lament 14 is shown as being connected through its lead wires and the conductor rods 5|. to conductors |55 and |56, the former of which is connected through an ammeter |51 to a conductor |58'which extends to a suitable source of current (not shown) for heating the filament. The conductor |56 is preferably connected through a variable resistor |59 to a conductor |60 which extends to the other side of the source of filament ycurrent supply. The amount of current traversing the filament 14 may thus be varied by adjusting the effective value of the resistor |59, and is indicated to the operator by the ammeter |51.

The iilament shield-63 is diagrammatically illustrated as being connected to one side .of the iilament 14, and the same side of the filament is connected through a conductor I 6| to the plates |62 of two triode electron tubes |63 which are preferably of the high vacuum type. The filaments |64 of the tubes |63 are connected in parallel with each other and are adapted to be' energized from a suitable source oi' current (not shown) through two supply conductors |65, one of which is connected through a conductor |66 to the negative side of a source of direct current potential that is to be applied to the filament 14 and the shield 63 on the one hand, and the electrode 69 on the other hand.y The positive side of vthis potential source, which, as is indicated on the drawings, may suitably have a value of 100 to 2,000 volts, is connected through a con- The negative electrode 69 to the negative side of a source of relatively high direct current potential, which, for example, may be of a suitable value between 100 and 30.000 volts, as indicated on the drawings. The positive side of this high potential source is connected through a conductor |68 to the positive electrode 80 of the oscillograph, and is also preferably grounded, as indicated at |69.

' The connection from the conductor |61 to the negative electrode 69 is made by means of a binding post or screw |10, which, as indicated in Figs. l, 2 and 3, is suitably mounted on the metal material because all of the portions of the casing below the insulating portion 28 are oi metal and are in contactwith each other, except on comparatively rare occasions when an insulating tubular section carrying a beam-deecting electromagnet is secured between the parts |04 and |05 of the casing as above mentioned. In view of this factV the grounding of the conductor |68. as indicated at |69 in Fig'. 13, is a material factor of safety for the operator, because none of the portions of the casing is electrically energized above ground potential except the upper casing portion 21, which is protected by the four insulating rod portions 32h. A

lOne of the deiiecting plates 00 is connected through a conductor |12 to a timing oscillator or other suitable source of timing potential, one form of which is described hereinafter, and the other of this pair of plates is connected through a conductor |13.to ground, to which the other side of the timing circuit will also be connected. In this manner a suitable timing potential is applied to this pair of deiiecting plates, as previously described. One of the pair of deliecting plates 9| is connected through a conductor |14 Yto ground, while the other of this pair of plates is connected through a conductor |15 to an antenna |16 that is suitably suspended between a high-potential transmission line |11, or other conductor that is to be subjected to the phenomena under observation, and a grounded counterpoise |18. In this manner the antenna |16 is subj ected to the lightning surges or other abnormal conditions occurring on the line |11 without being directly connected to said line, by reason of the disposition of the antenna in the electrostatic field between the line |11 and the counterpoise |18. If desired, the antenna |16 and counterpoise |18 may be replaced by a dividing condenser to accomplish the same result. Accordingly, an electrostatic field of varying intensity depending upon the conditions obtaining in the line |11 is created between the two defiecting plates' 9|. The conductor |15, antenna |16 and the plate 6| to which the conductor'l15 is connected, are preferably grounded through a resistor |19 of the magnitude of 5,000,000 to 10,000,000 ohms to prevent the accumulation of an excessive static terminal of the battery |82 is connected to a conductor |83 extending between one terminal of each of two secondary windings |84 of a transformer |85, which is preferably of the air core type. This' transformer further'comprises a primary winding |86 having one of its terminals connected to ground through a conductor |81, and having its other terminal connected through a conductor |88 to a second antenna |89 that is disposed similarly to the antenna |16 between the high voltage line |11 and the grounded countei-poise |18. 'I'he outside terminals of the secondary windings |84 of the transformer |65 are respectively connected through conductors |90 to the grids |8| of the vacuum tubes |63.- y

With the above described connections, the grids ISI of the vacuum tubes |63 are normally negatively biased with respect to the laments |64 by the C battery |62, this negative bias being transmitted through the conductor |88, the-secwhile ondary windings |84 of the transformer |85 and the co ductors |80 to the respective grids |8i, e positive side of the battery is connected to the iilaments |64 through the conductor |8| and the balancing resistor |80. By reason ol' this negative gridbias inrthe tubes |63, the potential between the conductors |66 and |61, which must be applied to the iilament 14, or its shield 63, and the' negative electrode 69 to establish the cathode ray or beam |54 in the oscillograph, is cut oil from the instrument because no current can flow between the conductors |6| and |66 while the grids |9| of the vacuum tubes |63 are properly or suiilciently negatively biased with respect to the laments |64 of these tubes.

Since the beam voltage supplied through the conductors |66 and |61 is thus effectively cut off from the oscillograph by the valve actionof the tubes |63, the filament 14 of the oscillograph may be continuously maintained in a heated condition Aand the relatively high voltage between the conductors |61 and |68, which are respectively connected to the negative electrode 60 and the positive electrode 80 to establish an accelerating and focusing electrostatic eld therebetween, may be continuously connected to these electrodes so that this field is continuously maintained. The timing potential circuit, of course, may also be continuously connected across the deiiecting plates 90 Without having any effect upon the instrument, and the lm or viewing creen |42 may be maintained in operative posit on to record or indicate the deiiections of the cathode ray" or beam |54 as soon as the same is established and as long as it is maintained.

Therefore, all that it is necessary to do to place the oscillograph in operation for recording or observation of the phenomena occurring on the line |11 is to apply the proper voltage between the lament 14, or its shield 63, and the negative electrode. This is accomplished by means of the circuits through the vacuum tubes |63 because the negative bias on either or both of the grids |9| is overcome by the potential induced in the secondary circuits of the transformer |85 upon the occurrence ofsa surge in the line |11,

which causes current to traverse the primary winding |86 of this transformer because this primary winding is connected between the antenna |89,l disposed adjacent 'the line |11,and ground. The time required for establishment of the beam voltage between the filament 14, or its shield 63, and the negative electrode 69 is negligible with this arrangement `and is only thatrequired for electrostatically charging the circuit portions between which the potential is to be applied. The instrument andrelated circuits are so designed that-their electrical capacity is'extremely small, and it has been found in actual practice that the time required for building up the voltage for initiating the beam is not over one-half of one one-millionth of a second and may be as small as a quarter of one one-millionth of a second. It

-will be readiy appreciated that this amount of delay in bringing the instrument into operation is negligible in practice and will not effect a loss of any appreciable portion of the wave front of the phenomena to be recorded, even though these phenomena -are of extremely short duration, as in the case of surges caused by lightning.

When the beam voltage is applied to the oscillograph in the manner described, the cathode ray or beam |54 is immediately established and is .accelerated downwardly through the electrostatic field between the negative electrode 66 and the 75 positive electrode 80, and thence downwardly'between the two pairs of defiecting plates 90 and 9| to impinge upon the iilm or the screen |42. The timing potential applied between the plates 90 causes the beam to be deiiected transversely of the iilm or viewing screen and the electrical Ycharacteristic or phenomenon," that is to be recorded or observed creates a varying electrostatic field between the two delecting plates 9| whereby the beam is deflected in a direction normal to the direction of the timing deflection of the beam..

ary windings |84 are of opposite polarity with respect to each other to permit the establishment of the oscillograph potential circuit in response to the occurrence of a surge `of either polarity with respect to the ground. Y

When the surge isterminated, the primary winding |86 of the transformer |85 is no longer traversed by current and the C battery |63 therefore again becomes eiective to apply its negative bias to the grids I9| of the two vacuuml tubes |63. Thus, the potential between the conductors |66 and |61 is cut oi from the oscillograph just as soon as the surge or other phenomenon to be recorded or observed has terminated.

Another method whereby the oscillograph may be placed in operative condition in response to the occurrence of the phenomena to be recorded or observed is illustrated in Fig. 14, in which the4 several parts of the apparatus represented that are identical with parts illustrated in Fig. 13'are designated by the same reference characters that are applied to the corresponding parts in Fig. 13.

Referring to Fig. 14, it will be seen that the lament 14 is energized from a suitable supply of current through conductors |55, |56, |56 and |60 and the ammeter |51 and variable-*resistor |59 exactly as shown in Fig. 13. The lament shield 63, however, is not directly connected to either lside of the filament 14, but is insulated from said filament in a manner heretofore referred to. I'his result is accomplished in the construction of the oscillograph simply by extending three of the conducting rods 5| through the insulating cap 29A of vthe oscillograph casing instead of utilizing only two such rods, as indicated'in Fig. 4. O ne of the three rods 5| is connected to the lament vshield 63 through the metallic sleeve member 62 exactly as indicated in Fig. 4, and the lament lead 16 is connected to another.. one of the rods 5| through the insulated conductor 59 as also shown in this figure. The other iilament lead 15, however; instead of being connected to the metallic sleeves 62, 'is connected through a second insulated conductor similar to the conductor 59 to the third insulated rod 5| in a .manner which will be very readily understood.

With the filament 14 and its shield63 thus insulated from each other, it .becomes possible to apply a negative bias tothe shield with respect to the filament, and this is done by means of the vacuum tubes |63 in a manner similar to that in which these tubes interrupt the-circuit between the conductors |6| and |66 in Fig. 13.

shield .63.

One side of the iilament 14 is connected through .the corresponding conducting rod 5| and a conductor |92 to the positive terminal of a battery |93, the negative terminal of which is connected through two branches of a conductor |94 to the plates |62 of the vacuum tubes |63. The conductor |94 is also connected to one end o! a resistor |95, the other end of which is connected to the positive terminal of a second battery |96 and also, through a conductor |91, to the filament The negative terminal of the battery |96 is connected through a conductor |96 to one side oi the filaments |64 of the two tubes |63. A condenser |99 is connected in parallel with the battery |96 for the purpose of by-passing anyl inductance 4which may exist inthe internal connections of said battery, thereby hastening the building up of current in the tube circuits after a positive impulse has been received by the grids.

The iilaments |64 are energized as in the system illustrated in Fig. 13 through the conductors |65 extending to any suitable source of iilament current supply, and all of the remaining parts of the system, including the resistor |60, the C battery |92, the primary and secondary windings of the transformer |85, the grids |9| of the vacuum tubes |63, the antenna |69, the electrodes 69 and 60 and the deflecting plates 90 and 9| of the oscillograph, are connected in exactly the same manner as shown inFig. 13, and, therefore,

the conductors for establishing these connections` are indicated by the same reference characters as in Fig. 13.

It is to be noted, however, that the voltage between the lament shield 63 and the negative electrode 69 is continuously connected to these elements by means of the conductors |61 and |91, rather than being connected through the vacuum tubes |63. since these .vacuum tubes are now utilized to establish the cathode ray or beam in the oscillograph without interrupting the circuit by which this beam voltage is applied to the oscillograph. This is accomplished by normally main- .taining the filament 14 at a positive potential 'with respect to the shield 63 (which includes the member 18).- This positive potential is maintained by the battery |93, the positive terminal of which is connected directly to the iilament 14 through the conductor |92 and the negative terminal of which is connected to the member 63 through the resistor |95 and the conductor |91. When a surge, or similar phenomenon to'be observed or recorded, occurs on the line |11, the resultant positive energization of either or both of the grids of the tubes |63 permits current from `the battery |96 and condenser |99 to traverse the resistor |95. This establishes a potential drop across the resistor |95 in opposition to the potential of the battery |93. In th'is manner potential between the iilament 14 and its shield 63 may be brought to zero, or, if desired, may be overbalanced to make the shield positive with respect to the filament, with the result in either case that electrons from the filament are immediately permitted to pass through the opening 16a in the shield and to establish the beam for operating the instrument. 4

In a system such as those shown in Figs. 13 and 14, the vacuum tubes |63 are effective to prevent the establishment of the cathode ray or beam except upon the occurrence of the abnormal conditions or phenomena on the line |11 which it isI desired to record or observe. 4 The antenna |89 may be designated as a-controlling antenna,

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