US2266665A - Amplifier - Google Patents

Description

Dec. 16, 1941. I F. E. SUMMERS 6, 6

" AMPLIFIER f Fi led Aug. 14, 1935 ,INVQV Tog. WM W I A377 I ATTORNEY.

Patented Dec. 16, 1941 vireo STATES}: PATENT OFFICE AMPLIFIER Frank E. Summers, near. Memphis, Mo., assignor to Radio Corporation'of America, New York, N. Y., a corporation of Delaware Application August 14, 1933, Serial No. 685,033

20 Claims. (Cl. 250-275) This invention relates to improved tubes for radio communication. It is one of the objects of the invention to use in such tubes a conducting medium of alkali vapor produced from a plurality of alkali metals.

Another object is to provide improved means that will utilize the high photo-electric effects of alkali metals and their vapors.

Another object is to provide means whereby the photoelectric effect of alkali metals may be utilized in the dark.

Another object is to provide means whereby both the cathode and anode electrodes of a tube will discharge electrons.

Another object is to provide a cold cathode tube, having two plate electrodes disposed in opposed relation to each other, each being coated electron emitting electrode.

Another object is to provide improved means .30

whereby all of the electrodes of an electron tube emit electrons or ions.

Another object is to originally coat a grid electrode, or an anode electrode, or both, with a are efiicient secondary or primary electron emitters.

Another object is to provide means for increasing the internal capacity between the anode electrode or the input grid electrode and the cathode electrode by a direct electrical connection of another grid or control electrode to said cathode electrode.

Another object is to shunt the internal capacity of a radio tube around the electron emission so that the internal capacity does not affect detrimentally the internal conductivity of the tube. This object is attained by electrically connecting the inner, outer, or one of the other grids directly to the cathode electrode.

Another object is to provide means to increase the efiiciency of radio tubes by the use of a double terminal grid electrode coated originally with an electron emitting compound and adapted to operate at ordinary room temperature.

metallic salt whereby said electrodes thus coated .35

Still another object is to provide means Whereby the visible and invisible rays of radium will cause the photo-electric efiect of alkali metals to take place.

Another object is to provide a direct electrical connection between two electrodes of a radio tube, other than the anode electrode, whereby improved amplifying action with stability is obtained.

Other objects of the invention will appear more fully hereinafter. The invention consists substantially in the construction, combination, location, proportion, and relative arrangement of parts and circuits, as will be more fully hereinafter set forth, as shown by the accompanying drawing, and finally pointed out in the appended claims.

This application is a substitute or a continuation of my now abandoned application Serial No. 684,545 filed January 5, 1924 and a continuationin-part of Serial No. 423,737 filed January 27, 1930.

The same reference characters designate the same or equivalent parts wherever they occur in the several figures of the drawing.

My invention will be described with reference to the drawing accompanying and forming a part of this application, and in which the figures represent diagrammatically various arrangements of apparatus and circuits wherebymy inventions may be carried into effect.

Fig. 1 discloses a four electrode tube and circuit, with a gas burner to heat same.

Fig. 2 discloses a two electrode tube and circuit.

Fig. 3 discloses an enlarged view of a portion of a pointed electrode coated with a radio-active substance.

. Fig. 4 discloses a modified form of a three electrode tube.

Fig. 5 discloses a modified form. of a three electrode tube with a non-inductive electrical winding'to heat said tube.

Fig. 6 discloses a three electrode tube having pointed cathode and anode electrodes.

Fig. 7 discloses a three electrode tube having a free alkali metal or metals and vapor or vapors disposed therein, and circuits associated there- 0 With.

Fig. 8 is an enlarged view of a filament coated with a light emitting substance and an alkali metal.

Fig. 9 discloses a three electrode tube having a filament disposed between a plurality of plate electrodes and a free alkali metal and vapor therein, and circuits associated therewith.

Fig. 10 discloses a modified form of the system shown in Fig. 1.

The embodiment disclosed in Fig. 1 shows a four electrode tube provided with an envelope l and having a plurality of input circuits connected to a plurality of double terminal grid electrodes. The antenna is connected to variable condenser 8, then to primary winding P of loose coupler 5 and conductor I0, the primary being grounded by way of a variable tap through the conductor 9. The conductor I is connected to upper grid electrode 4 and through the conducting medium 39 of tube I to electrode 3, conductor I I, secondary winding S, then inductively to primary winding P. Th secondary circuit is constituted by the secondary winding S, conductor alloys of these metals.

II, electrode 3, conducting medium 30, lower 1 grid electrode 4, conductor 20, variable condenser 4, and conductor I8 back to said secondary winding. The lower grid 4 is preferably coated with an electron emitting substance. The primary and secondary circuits above described comprise a pair of inductively coupled input circuits. The plat circuit comprises electrode 3, conductor I2, telephone receiver 6, conductor I3, variable condenser I4, B battery, electrode 2 and conducting medium 39. The electrode 3 in this embodiment is radio-active and electrode 2 is composed of an alkali metal. The rays emitted by the radio-active electrode 3, the heat and light from the gas burner I5 and the photoelectric effect of the alkali vapor from electrode 2 this tube to operat on a very small B battery. Switches 32 and 33 are for the purpose of connecting the upper grid 4 direct to the cathode 3. I have found that this serves to increase the internal capacity of radio tubes and hence the amplification. The numeral I represents the seal of the tube after evacuation has been accomplished.

The embodiment disclosed in Fig. 2 comprises a two electrode tube I having the electrodes 3 and 2 connected serially to the secondary winding S by conductor II, B battery, conductor I9, electrode 3, conducting medium 3!), electrode 2, conductor 20, telephone receiver 6 andv conductor I8. The B battery and telephone receivers are each shunted by a condenser IT. The electrode 3 is radio-active and the electrode 2 is composed of an alkali metal or metals, combined with some radio-active substance 3.

The radio-active electrodes are preferably composed of or coated with one or more of the following: 'pitchblende, uranium, thorium, radium, ionium, mesothorium-I, actinum, radium-D, radiothorium, and radium paint. One example of radium paint is phosphorescent zinc sulphide, combined with a very small quantity of radium bromide or chloride. For instance, if any of the electrodes were coated with this electron emitting paint, the electrode would visibly glow in a. vacuum tube for a very long period. It is to be understood also that one or more alloys of above elements may be used for a single electrode.

An example of a cold light or electron emitting substance is phosphorescent zinc sulphide; another example is the electron or light emitting compound of radium bromide and phosphorescent zinc sulphide. The light from the cold light emitting substance causes one of the electrodes to emit electrons, and this electrode may be used as a cathode. Also, the conductivity of a vacuum tube is increased by the use of a non-radio active cold light emitter electrode. Cold tubes of this class may be used as detectors, amplifiers and for the rectification of alternating or oscillating current.

The alkali metal electrodes or vapors used in the tube envelope are composed of caesium, rubidium, potassium, sodium, and lithium, or

Also, it is to be understood that these metals may be used inside the tube in the form of a deposit, or else the vapor of a plurality of alkali metals may be used. Both the alkali metal itself and its vapors are sensitive to the photo-electric efiect.

. The embodiment disclosed in Fig. 3 is a portion of the pointed electrode 3 shown in Fig. 2. The points 2' which may be of a non-oxidizable substance are coated with a highly radio-active material 3' such as radium paint. The plate portion of electrode 3 may be composed of tungsten coated partially with uranium and radium paint.

The embodiment disclosed in Fig. 4 comprises a casing or envelope I filled with alkali vapor and a plurality of electrodes 2 which are composed of an alkali metal. In this disclosure both the cathode and anode electrodes are composed of an alkali metal or metals or alloys of same. The upper electrode 2 is preferably the main cathode or primary electron emitter, and the cold double terminal grid 4 and the lower electrode 2 are secondary electron or ion emitters. One of the alkali metal electrodes may be coated partially with a radio-active substance 3 which increases the photo-electric effect.

I also want to make it understood that alkali vapor is repelled from both the cathode and anode electrodes, probably as electrons from the cathode and as ions from the anode. Thus, both the cathode and anode electrodes act as discharge electrodes. Probably the electric circuit is largely completed by the collision of negative electrons and positively charged ions.

The embodiment disclosed in Fig. 5 has the double terminal filamentary cathode-grid 4 disposed between the two cold electrodes 3 and 2 which are disposed in an atmosphere of alkali vapor. The cold double terminal cathode-grid 4 may be of tungsten or tungsten coated with a radio-active element, a radio-active compound, or any alkali metal disclosed in this specification. The single terminal electrode 3 may be composed in part of a radio-active element, a radio-active compound, or a radio-active sub stance and an alkali metal. The double terminal cathode-grid 4 and the single terminal electrode 2 may be coated with one or more of the elements, alloys or compounds mentioned in this specification. The non-inductive winding 2i provides external electrical non-magnetic means to heat the cathode 2 or 2. It is to be understood that the alkali metal vapor 30 in the casing I may be used at any preferable pressure.

In Fig. 6 the embodiment shown comprises a plurality of electrodes 3 which may or may not be radio-active, the points 2' of said electrodes being coated preferably with a radio-active substance 3'. A grid 4 is coated with an electron emitting compound and disposed between said electrodes. All of above electrodes are disposed in the envelope I containing an alkali vapor. These electrodes may also be coated partially with an alkali metal or metals or alloys of same, or other eflicient electron or ion emitting material. Each of the plate electrodes 3 is preferably composed of tungsten coated partially with an efficient electron or ion emitting material or materials. I

The embodiment disclosed in Fig. 7 has preferably a double terminal filamentary cathode 3 which is composed of a tungsten base, combined or alloyed with a percentage of uranium. Since the method of making such filamentary cathodes is well known it will not be further described.

a metallic salt and may be of any preferred form. I

In this tube 'a photo-electric effect takes place. The cathode and anode electrodes being disposed in an alkali vapor, the photo-electric effect will take place from both electrodes. When this tube is cold there is the photo-electric effect caused by the radiactive cathode, then when the A battery is turned on there is added the thermoelectric effect caused by heat, and then when the filament begins to glow there is further added the photo-electric effect caused by visible light, all three of these forces operating simultaneously to cause sufiicient electron emission at a very low temperature and low filament current consumption. When the filament has a coating of radium-paint applied to it very little, if any, heat need be applied to the filament. This tube will be more stable if a non-inductive means is employed to heat the tube from the outside, as shown in Figures 1 and 5. This is because the emission of vapor in a closed place is retarded and finally ceases when the saturation-pressure is reached. If the filament temperature is not enough to bring the vapor pressure to the required saturation-pressure, then exterior heating means may be used. The saturation-pressure required for efficient stable operation can be controlled largely by the degree of evacuation and the nature and temperature of the heat applied. In Fig. 3' there is shown an enlarged portion of the filament of Fig. 7. It is composed of some refractory material such as tungsten coated with radium-paint 3' and alkali metals 2. The filament or electrode base 3 may be purely of tungsten or composed of tungsten and metallic uranium.

The circuit disclosed in Fig. 7 is more fully described in the above mentioned applications. When the grid electrode in Figs. 1 and 7 is provided with a direct electrical connection to the cathode by way of one or more switches, the inner capacity of the tube elements is greatly increased. In one modification of Fig. 7 the grid or control element is used as the output electrode by connecting a source of electrical energy and a telephone receiver directly in the grid circuit.

The circuit disclosed in Fig. 9 comprises a plurality of inductively coupled input circuits. In this circuit a telephone receiver may be connected in either or both of the jacks 6. All three electrodes are electron discharge electrodes. The control plate 4 and double terminal electrode 3 are both cathode electrodes or grid-cathode electrodes, and the plate 2 is the anode electrode.

Figure 10 is a modification of Figure 1 wherein the switch elements 32 and 33 are omitted and a solid wire connection is used instead. In my earlier application No. 684,545 the switch 33 was forselectively connecting the grid direct to the .cathodebr for connecting a positive source of electrical potential to the inner grid electrode,

similar to Fig'ure 7. A variable non-inductive resistance [4'- and a condenser in shunt thereto are included in the plate or anode circuit.

In Figfll'the binding post I6 at the top of primary winding P 'of transformer 5 and the binding post [6 at the top of transformer 23 are for connection to an aerial. It is obvious that when an aerial is connected to the binding post "5 of transformer 23, the latter will then be in the input circuit, and the closing of switches 34, 35, and 3'! shunts out of use or short-circuits the primary winding and the secondary winding of transformer 5, and the grid 4 will then be directly connected electrically to the negative side of the cathode 3. This inherently increases the inner capacity of the cathode 3 and the anode 2 and hence the amplification. An example of another modification is where the aerial is connected to the binding post [6 of transformer 23, switches 35 and 31 are open and a telephone receiver is plugged into jack 6. The conductor or circuit I8 is then the output circuit, conductor [8 then having connected serially thereto battery B and the three pole rheostat 25. The inductance 23 in the anode circuit causes the system to oscillate or regenerate, the B battery voltage required to produce oscillation or rengeneration being greatly reduced by the use of an anode 2 composed in part of metallic lithium. The lithium grid 4 is the output electrode of the known dynatron oscillating system and the anode 2 serves as the input electrode. It is obvious that this description describes only a few of many modifications made possible by the various switches, binding posts, circuits and other elements disclosed.

In lieu of alkali metal electrodes, the alkali metal may be deposited on the electrodes and inner wall of the glass tube casing.

The new features herein described and claimed and differing from the art heretofore used are: an improved cold electron emitting grid electrode; a cold double terminal control electrode coated originally with an electron emitting substance, such as a metallic salt or compound; the increase in internal capacity of a radio tube by providing a direct electric connection between the cathode and a grid electrode; the increase in internal capacity of electron tubes by electrically connecting one of a plurality of grid electrodes direct to the cathode; the coating of any electrode of a radio tube with the metallic salts, radium-bromide, radium-chloride, and zinc sulphide; by providing photo-electric devices using a plurality of elements or compounds that are sensitive within, above and below the visible spectrum, thus making a greatly improved efficient device; and other features herein described.

It is obvious that this invention may be embodied in a three element tube having three cold electrodes, or a three element tube having two cold electrodes and a single hot electrode, or having a plurality of hot electrodes and a single cold electrode, all capable of emitting electrons or ions. It is further obvious that my invention comprises an electron radio tube have a primary electron emitting cathode and one or more cold electrodes which are efiicient ion or secondary emitters. One inherent operation of my tube is that when in use the compound used on the grid or anode electrodes, or both, is chemically reduced to its constituent elements.

An important function of my invention is that, in connecting a grid electrode direct to the oatho'de electrode, the internal capacity of the tube is shunted around a part of the electron flow or electron emission, so that the internal capacity does not aifect a part of the conducting medium of said tube, resulting in far better and more stable amplifiers, and especially so, when regeneration or multi-tube stages of radio-frequency amplification are used.

In Figs. 1 and 7 I have. shown conductors connecting a cathode electrode to a grid electrode having substantially no inductance, impedance, ohmic resistance, or a source of electropositive energy.

In this specification and claims, the terms, direct electrically, electrical means to directly connect, or direct electrical connection, include methods of connecting two electrodes of a a radio tube together, such as by a relative short wire, or wires, or by a continuous connection by means of one or more switches, They do not include the old electrical connections of electrodes such as by the medium of an inductance, dry cell or battery, grid-leak, impedance, condenser, or a combination of these elements.

In practice it is preferable to coat the grid or anode electrodes with the cold ion emitting substance or substances before the electrodes are placed into the envelope, or before said envelope is permanently evacuated, or at any suitable stage during the process of manufacture. The cold ion emitting substance or substances is or are preferably coated or formed on one or more of said electrodes substantially before the stage of manufacture is completed.

It is also obvious that this invention may be embodied in a tube having two, three, four or more electrodes. The electrodes may be of any preferred form such as a filament, flat or pointed electrodes.

Also certain embodiments of this invention will generate an electro-motive force and, to a certain extent, will operate as a detector and amplifier without any A or B batteries. Being the combination of a tube and electric cell, this is accomplished by the use of a non-oxidizable electrode and an oxidizable, electrode subjected to the action of alkali metals or vapor. This oxidizing action is increased by the use of radioactivity, light, heat, and other invisible waves.

Other examples of radio-active substances are salts of uranium, and other elements that are radio-active. Also polonium and carnatite may be used. The salts of metallic metals are metallic compounds, whose names end in ate, ide, and ite. Thus, examples are radium-bromide, zinc sulphide, thorium-sulphate, uranium-oxide (pitchblende or uraninite), thorium-oxide, sodium-uranite, and similar salts; of course, metallic salts should be used that are reasonably inert to other elements and compounds used in radio tubes. Many of the metallic salts are unstable in the atmosphere, while there-are many that are stable.

It is also to be understood that any alloy of alkali metals may be used as an electrode or vapor. If the alloy of sodium and potassium is used in proportion to their combining Weights, there results a mercury-like fluid which may be used in the casing as a vapor, or both as an electrode and vapor.

The tubes according to the invention may be used as detectors, oscillators and amplifiers when connected in proper circuits. Also a flame or other non-magnetic means may be used to heat any of the tubes. In certain embodiments the conducting medium should not be under the influence of magnetism.

The spirit of this invention includes the direct electrical connection of two electrodes, except the anode, of a radio tube together by one or more serially connected electric switches, or by solid wire connections, or by all equivalent connections. Such old elements as an inductance, impedance, grid leak, condenser, or a source of electrical energy, are not involved singly or in combination serially in said connection. The said cathode-grid connections of course may be made within the tube envelope, outside of the tube envelope, on or within the tube base or within the socket. I first filed the invention of connecting the cathode electrode direct to a grid electrode in my application Serial No. 444,985 filed February 14, 1921.

Having described my inventions what I claim as new and desire to secure by Letters Patent of the United States of America is:

1. An electric discharge device comprising a casing containing a plurality of electrodes, one of said electrodes being composed in part of a phosphorescent substance and analkali metal.

2. An electric discharge device comprising a casing enclosing a plurality of electrodes, one of said electrodes being composed in part of a compound of radium-bromide and zinc sulphide.

3. An electric discharge device comprising a casing enclosing a plurality of electrodes, one of said electrodes being composed in part of radium bromide, zinc sulphide and an alkali metal.

4. An electric discharge device comprising a casing containing a plurality of electrodes, and one of said electrodes being composed in part of a radio-active element, radium bromide, zinc sulphide, and an alkali metal.

5. An electric discharge device comprising an envelope containing a plurality of electrodes, one of said electrodes composed in part of uranium, radium bromide, zinc sulphide and an alkali metal.

6. A photo-electric device comprising an envelope containing a plurality of electrodes, one of said electrodes composed of tungsten, a radioactive element, radium bromide, zinc-sulphide, and a plurality of alkali metals.

'7. An electron discharge device comprising an envelope containing an electron emitting cathode electrode, an anode electrode and. a plurality of cold double terminal control electrodes and each of said double terminal control electrodes having formed thereon a metallic salt whereby said control electrodes thus formed are eflicient emitters of ions.

8. A vacuum tube containing a cathode, plate and a plurality of grids, and one of said grids coated substantially with a metallic compound and an alkaline element whereby the electrode thus coated is an eflicient emitter of electrons.

9. A vacuum tube containing a cathode, a plurality of grid electrodes and a plate electrode, one of said grid electrodes coated substantially with a metallic compound whereby the electrode thus. coated is an efficient emitter of ions and electrons.

10. A photo-electric device comprising an envelope having a cathode electrode coated with a film of uranium, and an anode electrode disposed therein.

11. A photo-electric device comprising an envelope containing a cathode electrode coated with uranium and an anode electrode coated with lithium.

12. An electric device comprising an envelope and containing a double terminal filament capable of operating at incandescence, and said double terminal filament composed in part of uranium, whereby said filament sends out ultraviolet light.

13. A radio tube comprising an envelope containing two plate-cathode electrodes disposed parallel to each other, and said plate electrodes coated partially with a photo-sensitive material whereby said electrodes thus coated are efiicient emitters of electrons, and a grid electrode disposed between said plate electrodes.

14. A radio tube comprising an envelope containing two plate electrodes disposed parallel to each other, and said plate electrodes coated partially with uranium-oxide, and a grid electrode disposed between said plate electrodes.

15. A radio tube comprising an envelope containing two plate electrodes adjacent and parallel to each other, and said plate electrodes composed of tungsten coated partially with an alkali metal and uranium oxide, and a grid electrode disposed between said plate electrodes.

16. A radio tube comprising an envelope containing two plate electrodes disposed adjacent and parallel to each other, and each of said plate electrodes coated partially with a photo-sensitive substance and a radio-active substance, and a third electrode associated with said plate electrodes.

17. A radio tube comprising an envelope containing two plate electrodes disposed adjacent and parallel to each other, each of said plate electrodes coated partially with caesium, and a grid electrode disposed between said plate electrodes.

18. An electron discharge device comprising an envelope containing a cathode electrode coated with uranium-oxide, and an anode electrode.

19. An amplifier comprising an envelope having a single terminal cathode electrode, an anode electrode and a plurality of grid electrodes disposed in said envelope, one of said grid electrodes being coated with an eflicient electron emitting substance, and metallic means to connect said grid electrode thus coated direct electrically to said single terminal cathode electrode.

20. An amplifier comprising an envelope having a single terminal cathode electrode, an anode electrode, and a plurality of grid electrodes disposed in succession between said electrodes, said grid electrode that is disposed nearest to said cathode electrode being originally coated with an efficient cold electron emitting substance, and electrical means to connect said cold electron emitting grid electrode directly to said single terminal cathode electrode.

FRANK E. SUMMERS.

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