US1891475A - Discharge tube electrode - Google Patents

Description

Dec. 20, 1932. F. HOTCHNER DISCHARGE TUBE ELECTRODE Filed March so. 1929 .mVE/vToR Patented 2c, 1932.

UNITED STATES FRED HOTGHNEB, LOB ANGIHJES, CALIFORNIA DISCHARGE TUBE EIMUI'RODE Application filed larch 80, 1929. Serial No. 851,196.

This invention relates to a discharge tube electrode, and has for its object the roduction of an electrode such as might e used for ionization conductor lights. The elec- 5 trode of the present invention possesses certain desirable characteristics in the abovementioned use, being free from certain undesirable characteristics at present a problem in the art; these ends being accomplished by new and novel types of construction.

As at present understood by the applicant this device is new to the entire art of vacuous or vapor electric devices and its usefulness is not limited to ionization conductor devices, but also extends to devices essentiall v vacuous such as X-ray tubes. Therefore the disclosure has been contrived to enable one skilled in the art to understand the technique of the glass manipulation in the manufacture of the typical electrodes shown in order that the device can be reproduced and applied to devices of the cla$ mentioned. Further, to enable those skilled in the art to utilize this device as an electrode in gaseous discharge tubes, a theory is advanced of the operation of the same when so used. It is not intended to limit the invention to ionization conductor devices, thereby, nor is it intended to limit the invention by the theory of operation advanced. It is my intention that only such limitations be placed upon this invention as are imposed by the prior art and the appended claims.

movement of positive ions towards the emis 5 sion surfaces. The particular forms of the prior electrodes are characterized by a cylinder of conducting material, with a bore so reduced in diameter that the opposite surfaces within the cylinder neutralize each other in their effect on the ions formed. The

In several previously-filled co-pending ap plications I have disclosed electrodes fordischarge passes to the positive column thru an-orifice so constricted that such material from the electrode as is vaporized will not migrate out of the electrode chamber. It is also believed that the small orifice also prevents the space charge in the Faraday dark space region from being a factor in what goes on inside of the electrode.

One of the objects of the present invention is to provide an electrode of the general class described in which a greatly increased area of emission surface can be realized for a given volume of space. It is also an object to provide an electrode in which the opposing emission surfaces ma be made very close together without sacri cing in the available emission surface. In the case of cylindrical electrodes if this distance is reduced to a low value the total surface falls off and can only be increased by making the electrode very long. When this is done the current passing to the orifice from the deeper parts of the cylinder interferes with the action of the parts nearer the orifice. Hence a compromise must be made between an insulficiently small bore and the secondary action described. In the present invention the clearance can be reduced to an exceedingly small value without experiencing this difficulty and hence any desired extent of emission surface can be provided in a very small elecitrode and high current values can be use These results are accomplished in a construction which provides for the use of glass 35 as the shielding medium in such manner as to be readily understood by those familiar with. the construction of vacuum tubes or incandescent lamps. The vitreous elements are designed to finish in lines natural to the medium, thus providing for work that can be made accurate and will finish free from strain. The technique is also one that can be followed by bench fire work, semi-automatic or automatic machine production.

It is an important feature of the present invention, that in selecting a form of electrode which permits this treatment in the selection of material, I have also rovided a form of electrode which has an important physical idly moving away from the orifice. Thus acrowding eifect is produced resulting in a balancing component acting against the drift.

I have explained in previous applications the function of a constricted orifice toprevent the migration of evaporated material. In

. the present invention'I have provided means of five-eighths of an inch that this invention to make these electrodes with orifices of extremely narrow openings and for the finishing of the assembly with great accuracy, notwithstanding the refractory nature of the medium, with which we are working.

It is also an object to provide a greatly in- .creased extent of orifice in order to reduce the electrical stress in the material and per mit the use of ordinary lead glass for this purpose if desired.

' Further objects will become apparent from the description which follows.

An embodiment of the invention is shown in Figure 1. It is to be understood, however, may be made in many other forms than the particular form shown.

In Figure 2 a cross section is shown of the aperture, taken on the line 22, in Figure 1, enlarged.

Figure 3 is a perspective view, enlarged, of the inner cone and the inner shield.

Figure 4 is a sectional view of a mold for blowing the inner shield into the inner cone. The work is shown in the condition of completion of the blowing operation by broken lines.

Figure 5 is a View invention.

Numeral 1, Figure 1, indicates the end of the positive column section of a gaseous conductor discharge tube, ing tube, and numeral 10 indicates the enlarged electrode terminal thereof. This electrode can be made, if desired, small enough to be sealed into the end of the main tube without an enlargement. Assuming a tube diameter and consuming twenty-five thousandths of an ampere, this electrode could be made to fit into the end of the tube proper. Assuming a tube as above consuming one tenth of an ampere, the electrode would appear about as shown in Figure 1. The electrode proper of a modified form of the consists of the two concentric cones of conducting material 2 and 3, which are both conmam is open to the atmosphere of the tube thru 'the constricted orifice 7. This orifice is such as an illuminatnecte dthe lead-in conductor 7 4, which sealed thru the reentrant stein 5.

Thexcones are separated by a space 6 which properformed by-the shield 8,'an d the shield 9 which extend ast the end 11 of the emission surfaces. he shield 8 is inreality a bulbof glass which s blown into the inside of the inner cone 2, taking the form thereof and extending past the open end to form a wall of the orifice The shield 9 is a cone of glass fitted while cone 3, extending past the end and forming a wall of the orifice. At the small 'endthe shield 9 runs off into the stem 5 thus com pletely protecting the lead-in conductor 4.

hot to the outside of the outer When the compositions'of the shield and the stem are difl'erent and have a difi'erentcoefiiw cient of expansion, a section f intermediate glass canbe used between them as indicated by 12.

Decided advantages are gained by making the orifice as constricted as the character of.

the material will permit without the maximum variation bearing a substantial'proportion to the width of the opening. Thespacing is determined in this device by the bosses 13, 14, 15 and 16, formed from the material of the inner shield which bear against the outer shield and determine both the opening of the orifice and the spacing of the emission surfaces. The cross section in Figure 2 illustrates the function of the bosses. It will be appreciated that by blowin the shield into a mold such as is shown in igure 4 having depressions indicated by 17 and 18 for shaping the bosses that great accuracy can be secured. As shown by the broken lines in Figure" 4, the bulb is provided with a tubulation 19 and a blowing tube 20 which is separated at the tubulation after the bulb is blown.

The outer shield and the outer cone can also be formed over a mold by methods which are obvious. The lead in conductor is preferably brazed into the end of the cone 2 as indicated by 24 and the cone 3 can be pro-, vided with a collar at the small end indicatedby 21 which makes a tight fit over the lead in conductor. To provide for adhesion between the cones and the shields, the surfaces of the cones can be berated in the manner now common in the preparation of the surfaces of copper electrodes for gaseous conduction tubes.

y 120 In the form of the invention shown in in cross section being r trodes near the orifice are well protected by the shields and do not present any sharp corners to be attacked by the discharge.

Having thusdescribed my invention, what 5 I claim is.

1. In a discharge tube, a pair of electrode elements, having emission surfaces disposed parallel to each other and spaced a short distance apart, and a constricted orifice providing communication between the space within the chamber defined by the said surfaces and the main chamber of said dischar e tube.

2. In a discharge tube, a pair 0 electrode elements having emission surfaces disposed parallel to each other and spaced a short distance apart and an extended, constricted orifice providing communication between the space between said emission surfaces and the main chamber of said discharge tube.

3. In an ionization conductor discharge tube for operation on alternating current, an elongated envelope at the opposite ends of which are disposed electrodes, each of which is provided with a pair of elements having emission surfaces disposed parallel to each other and spaced a distance apart sufliciently small to reduce the movement of positive ions to a low value between said parallel disposed elements.

4. In an ionization conductor discharge tube for operation on alternating current, an

' elongated envelope at the opposite ends of which are disposed electrodes, each of which is rovided with a pair of elements havin emission surfaces disposed parallel to eac other and spaced a distance apart sufliciently small to reduce the movement of positive ions to a low value between said parallel disposed elements and shielding means separating said elements from the mam chamber of said discharge tube and a constricted orifice providmension parallel with said emission elements emission elements having surfaces dlsposed parallel to each other and spaced a short distance apart, the space between said surfaces having a cup-like form and said s ace being open to the atmosphere ofthe tu e proper thru a constricted orifice extending around the rim of said space.

9. In a discharge tube electrode, a cavity electrode element and another element formed to fit within the first said element and to be s aced from the same over the greater part 0 the opposing surfaces, the amount of said spacing being determined by.protuberances formed from at least one of said elements.

10. In a discharge tube electrode, a pair of emission elements of conducting material having a cup-like form, said elements being formed to nest one within the other with a small spacing between the near faces of said elements, a shield of dielectric material around the" outside element and extending past the open end thereof, and a shield within the inner element extending past the open end thereof.

FRED HOTCHNER.

ing comunication thru each shield for the 1 passage of discharges from the spaces be-' tween the said emission surfaces to the main chamber of said discharge tube.

5. In a dischar e tube, an electrode having a chamber in ,w ich two emission surfaces are disposed parallel to each other and spaced a short distance apart, and an opening out of said chamber into the main chamber of said discharge tube said opening consisting of a long constricted orifice the line ofthe longest dimension of said orifice extending parallel with said surfaces.

55 6. In a discharge tube, an electrode having a chamber within which is disposed a pair of emission elements havin surfaces disposed parallel to each other an spaced a short dis- :part, and dielectric shielding means. 5 dispos tance to confine the discharge to the surfaces within said chamber, there being an Q opening therethru providing a communication between the said chamber and the main chamber of said dischar e tube, said opening atively long in a di-

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