US1870975A

US1870975A - Cathode ray oscillograph

Info

Publication number: US1870975A
Application number: US305295A
Authority: US
Inventors: Ulrey Clayton Tridle
Original assignee: Westinghouse Lamp Co
Current assignee: Westinghouse Lamp Co
Priority date: 1928-09-11
Filing date: 1928-09-11
Publication date: 1932-08-09
Anticipated expiration: 1949-08-09

Description

Aug- 9, 1932- C. T. ULRl-:Y 1,870,975

CATHODE RAY oscILLoGRAPH Filed sept. 11, 1928 2 sheets-sheet 2 gull; /37 y zum " Eig. df-

.INVENTOR C T. ULREY ATTORNEY Patented Aug. 9, 1932 UNITED STATES PATENT OFFICE."

CLAYTON TRIDLE' ULREY, OF EAST ORANGE, NEW JERSEYfASSIGNOR 'IO WFS'IING?I i HOUSE LAMP COMPANY, A\COR?ORATION F PENNSYLVANIA.

CATHODE RAY OSCILLOGRAPH Application fuea september 11, 192s. serial No. 305,295.

This invention relates to a cathode ra oscillograph and more particularly to suc a device with which photographic lmaves of the form of current and voltage varlation with time, in an electrical circuit, may be obtained.

Cathode ray oscillographs emplo ed heretofore forv the determination of suc current or voltage variationsv have been essentially of' two types. In one type, a fluorescent screen is contained inside a sealedI glass envelope. This constructionlimits the use of the oscillograph to the examination of slmple wave forms, combinations of which will cause the cathode rays to trace Lissajou figures on the screen, or by the use lof auxiliary devices to cause a section of a wave train tobe repeated over the same path a large number of times. In another type, the wave trace is recorded on a photographic plate placed in side the apparatus but this requires the operation of the oscillograph while connected to a vacuum pump and the insertion of a plate in the evacuated device for exposure and the removal of the plate therefrom for development. This 'is troublesome and requires an involved exhaust procedure of the device and restricts the use of such oscillographs very greatly.

Other types of oscillographs depending upon the motion of a coil in connection with a rotating mirror or a moving photographic film to give the wave form of an electric current are not capable of recording high frequency changes in the electric current, due to c the inertia of the moving parts.

The cathode ray beam will respond to the highest frequency obtainable in an electric circuit and it is one of the objects of this invention to employ this property of cathode rays to producev an oscillograph in which the cathode ray beam traces its path upon a sensitized photographic material disposed outside of the tube.

Another object is to produce a cathode ray oscillograph in which a single train of waves or other electrical variations of high frequency and of either simple or complicated form may be photographed.

In accordance with my invention I produce a cathode ray oscillograph employing a to produce a stream of high velocity electrons. ,The electron stream is deflected by an electrostatic field in accordance with the current or voltage variations bein studied and a window is provided in the tu e, in the path of the electron stream which, while vacuum tight, is pervious to the high velocity electrons. Externally of the tube I arrange a photographic film or other sensitized material positioned close to the window so thatthe beam of electrons' traversing the window will trace the form of the current or Voltage variations with time on the sensitized material. The photographic film may be moved to spread the wave form over the film or the oscillating cathode beam may be deflected by an electric or magnetic field to distribute the wave form over the surface of the film.

In order that the invention may be more fully understood, reference will be had to the accompanying drawings in which,

Fig. l is a perspective view, partly in section of a cathode ray oscillographic tube embodying my invention and emplo ing a moving film upon w ich the oscillogram is traced;

Fig. 2 is a sectional View of the anode end of the device of Fig. 1 showing the film carrying container and,

Fig. 3 is an elevation, partly in section, of an oscillographic tube employing a stationary film.

Fig. 4 is a sectional View of a. modified form of oscillographic tube.

The oscillographic tube shown in Fig. 1 comprises an envelope 1 of glass containing an electron emitting cathode 2, and anode 3, and a pair of insulated

parallel metal plates

4 and 5; The cathode consists of a coiled filament arranged normal to the axis of the tube and supported within the envelope by supporting Wires 6 and 7 sealed in the press 8 of a reentrant glass stem 9 sea-led to the bulb. A metallic sleeve 10 disposed about the supporting wires 6 and 7 and the cathode 2 has a linear slit 11 arranged adjacent the cathode, parallel to land in line therewith so as to produce a line beam of cathode rays. The sleeve 10 is supported by the stem 9 and serves as a shield to protect the press and to prevent, sparking and sharp point discharges from the cathode and cathode leads,

The anode 3 consists of a metallic cylinder sealed to the glass envelope as at 12 and having a portion 13 extendin exteriorl of the envelope. The end 14 o the ano e is closed and has a narrow slit 15 arranged at right angles to the slit 11.

The slit 15 is covered by a window 16 of thin material, which is pervious to cathode rays and is sealed to the anode in a vacuum tight manner.

The

plates

4 and 5 are supported on opposite sides of the path of the cathode stream by supports 17 sealed through the envelope at 18.

The cathode 2 may be heated to an electron-emitting temperature by a battery 18.

When direct current of sulicient potential is applied between the cathode and anode, as by

wires

19 and 20, the cathode rays originating at the cathode 2 will emerge through the slit 11 in a line beam which, when no voltage is applied to the plates 4 and'5, will be disposed centrally of the slit l5 and at right angles thereto so that a narrow concentrated beam of rays will pass through the foil and emerge into the open air. When a variable potential is applied between the plates the line" or band beam will be deflected so as to move along the slit 15 in accordance with the impressed variable potential due to the electrostatic field produced between the

plates

4 and 5. This will cause a concentrated beam of cathode rays to emerge from the window 16 and to 'fluctuate back and forth in line with the window, the amplitude of which fluctuation corresponds to the strength of the variable voltage applied to the plates 4 andv 5. ,Y l.

A strip of sensitized photographic material 21 may be mounted in a light proof box 22 u on

reels

23 and 2 4 so that it may be rapi ly moved ast the slit 15. The direction of travel o the sensitized material is at right angles to the slit 15.

Assuming, by way of example, that it is desired to measure the wave form of the output of the secondary winding 25 of a transformer 26, the ends of the secondary winding may be joined electrically to the

plates

4 and 5 so as to charge up the same in accordance with the output of the transformer. If a potential is then applied between the cathode and the anode sufficiently high to produce electrons of a velocity which will penetrate the window 16, the electron stream will bev deflected in accordance with the potential changes in the output of the transformer and if the sensitized strip 21 is moved rapidly past the slit 15 a permanent trace of the Wave form will be recorded. The box 22 may then be removed from the end of the oscillographic tube and the sensitized material readily removed.

The voltage between the cathode and anode required to propel the electron stream through the window 16 depends upon the thickness of the window and the density thereof. With an aluminum foil or glass window having a thickness of from .00025 to .0003 inches a potential of the magnitude of about 30,000 volts is required to cause the electron stream to pass through the Window. With molybdenum foil of the same thickness much higher volta es are required, due to the much greater density of molybdenum.

The electron stream upon emerging into the atmosphere is dispersed to some extent by collision with the gas molecules in the air and in order to render the oscillogram sharp it is necessary to dispose the ilm 21 as close as practical to the Window as, for instance, about 1 mm. In order to increase the sensitivity of the device the

parallel plates

4 and 5 should be spaced close to the slit 11 so as to deflect The tube comprises an envelope 30 having l a reentrant stem 31 through which the lead wires 32 and 33 for the incandescent cathode 34 are sealed. The cathode 34 is mounted metal tube of nickel, Monel metal, chrome iron, etc., lheld in place on the reentrant stem v 31 by friction. Obviously, other convenient methods of support may be devised.

The anode consists of a tube 37, preferably l of copper and is provided with a leading-in conductor 38 sealed through the envelope, as

at 39. The tubular anode is supported in the envelope by a split collar 40 of chrome-iron or other suitable metal which fits snugly into the glass envelope and is secured to the anode by screws 41. The tubular anode is arranged with its axis aligned With the axis of the electron stream which is directed by th( fo cusing cup 35 centrally of the anode.

lnrs

of the oscillogram is dependent upon the size of the openings. v

Within the anode are placed a pair of' spaced

parallel plates

46 and 47 These plates are supported by

stems

48 and 49 passing through insulating bushings 50 in the anode.

The stems 48-and 49 are sealed through the envelope at 51 and 52 respectively. The

plates

46 and 47 correspond to the

plates

4 and 5 of the oscillographic tube shown in Fig. 1 and serve to deflect the cathode beam in accordance With the electrical conditions existing in the circuit under consideration, as the secondary of the transformer 26.

A second pairof

parallel plates

53 and 54 are mounted within the anode at right angles to the plates 461' and 47. The

plates

53 and 54 when charged o'ppositely, deect the oscillating cathode beam toward the more positively charged plate and if the charge is decreased, the oscillating beam will be caused to move vat right angles to the

plates

53 and 54. Thus, for instance, the plates may be connected by

wires

55 and 56 to a condenser 57 charged in any suitable mannerl not shown, so as to deflect the cathode beam towards one of the plates, as 53. l

If the condenser is ,allowed to discharge slowly, over an interval of time, as through a resistance 58, the cathode beam will be deflected away from the plate 53, so as to trace the wave form with time on a sensitized' photographic film 59 disposed externally of the tube closely adjacent the Window 60.

The window 60 in this embod1ment is of the type disclosed in a copending application of C. M. Slack', Serial No. 27 2,194, filed April 23, 1928 and entitled Cathode ray tube. This window consists of a bulbous glass portion sealed to the envelope and of extreme thinness, as for instance, 0.00025 inches. Glass of this thinness when formed of bulbous shape, will withstand atmosphere presanode and cathode may be supplied from any desired source by

conductors

62 and 63.

I have shown in F ig. 4, an oscillographic tube which is more sensitive than that of Fi g. 3. In this embodiment the deflecting field is caused to act upon the cathode beam before it has acquired a high velocity and the beam is subsequently accelerated so that it will pass through the Window to the exterior of the ltube.

In this device, a relatively low voltage `is applied to the anode 37 as by means of a buttery 38 so that the cathodebeam emerging from the orifice 45 is of relatively low velocity and therefore more readily deflected by the

parallel plates

46 and 47. In place of the deflecting plates 53 and 54 I have illustrated a deflecting coil 64 disposed externally of the envelope so as to deflect the cathode beam in a direction at right angles to the deflection caused by the

plates

46 and 47. When employing such a coil the tubular anode 37 should be composed of a non-magnetic material such as copper.

Such a deflecting coil may be employed in place of either of the sets of deflecting plates I shown in Figures 1 and 3.

In addition to the anode ond or supplemental anode, 65 to which a high potential may be applied by

conductors

66 and 67 for accelerating the cathode beam to glass window 60 and trace the oscillogram on the film 59.

The supplemental anode 65 preferably extends into the anode 37 in order to shield the Acathode beam from any undesired v.extern-al fields which might tend to deflect the beam.

With the construction shown in each of the embodiments it is possible vto vobtain oscillograms ofcurrent or voltage variations of high frequency and complicated form, and to record the same on a photographic film placed outside of the tube by the direct action of the cathode rays on the film.

It is obvious, of course, that various changes and modifications'may be made in the construction shown and described and I do not desire to 'be limited to the exact 'details thereof except in accordance with the appended claims. f

What is claimed is:

l 1.' A cathode ray oscillograph comprising an envelope, means therein for producing a beam of electrons of small cross section, a tubular anode, a window in said envelope in line with said beam of' electrons and permeable thereto, means for' deflecting said beam and means disposed externally of' the envel-` ope for directly recording the extent of the deflection of said beam.

2. A cathode ray.oscillograph comprising .a suliiciently high velocity to penetrate the l an envelope, means therein for producing a beam of yelectrons of restricted cross'section, an anode, a window in the envelope permeable to said beam of electrons and in align ment therewith, means for deflecting said beam and means disposed externally of the envelope sensitive to cathode radiations for producing an image of the path of deflection of said beam of electrons.

. 3. A cathode ray oscillograph comprising an envelope, means therein Jfor prod ucing a beam of electrons of small cross sectlon and high velocity, an anode having a restricted opening therein in alignment with said beam of electrons, a window in the envelope permeable to said high velocity electrons, electrostatic means for deflecting said beam and means disposed externally of the envelope sensitive to cathode radiations for producing an image of the path of defiection of said beam.

4. A cathode ray oscillograph comprising an envelope, a source of electrons of high velocity therein, a tubular anode, a window in said envelope permeable to said high velocity electrons, means for projecting said electrons through said window, means Within the envelope for delecting said electrons from their normal path in accordance with electrical conditions in an external circuit and means disposed externally of said envelope sensitive to cathode radiations for recording the-defiection of said electrons.

5. A 'cathode ray oscillograph comprising an envelope, a source of electrons of high velocity within said envelope, a tubular anode having a restricted opening therein in the path of said high Velocity electrons for producing a restricted beam of cathode rays, a window in said envelope permeable to said cathode beam and in line therewith, means for delecting said cathode beam and means externally of said envelope adjacent said window for directly recording the path of deflection of said cathode beam upon a photographic film.

6. A cathode ray oscillograph comprising an envelope, an incandescent cathode therein, a tubular anode, means for directing electrons from said incandescent cathode through said tubular anode, a window permeable t-o electrons, means for deflect-ing said electrons and means externally of said tube sensitive to cathode radiations for recording the defiection of said electrons.

7. A cathode ray oscillograph comprising an envelope, a source of electrons therein of high velocity, a tubular anode, a partition in said anode having a pair of aligned openings of small size, means for directing said electrons through said openings, a window in line with said electron stream permeable thereto, means for deflecting said electron stream and means externally of the envelope to intercept said deflected radiations and to record the eX- tent of said deflection.

8. A cathode ray oscillograph comprislng an envelope, an incandescent electron-emitting cathode therein, a tubular anode, a window permeable to cathode rays, means for directing a narrow beam of cathode rays through said window, means for delecting said beam and means externally of said envelope adjacent said Window adapted to be bombarded by said cathode rays to trace the path of deflection thereof.

9. A cathode ray oscillogra h comprising an envelope, an electron emitting cathode therein, a tubular anode, a window permeable to said electrons, means for producing a restricted beam of cathode rays, means for delecting said beam, and means disposed externally of said envelope in position to be bombarded by said beam for recording thel path of deiection thereof.

10. A cathode ray oscillograph comprising an envelope, a source of electrons therein, means including a tubular anode for producing a restricted beam of cathode rays, a window in said envelope permeable to said beam in line therewith, means for deiiecting said beam in accordance with conditions in an external electric circuit and means external of said window to photographically record the path of deflection of said beam.

11. A cathode ray oscillograph comprising an envelope, a source of electrons therein, an anode, means for producing a restricted beam of electrons, means for defiecting said beam, means for accelerating said beam of electrons to a high velocity, a, Window in line with said beamV permeable thereto and means positioned adjacent said window sensitive to said cathode rays to record the path of deflection of said beam. j

In testimony whereof, I have hereunto subscribed my name this 6th day of September CLAYTON TRIDLE ULREY.