US2446554A - Electrometer vacuum tube - Google Patents

Description

Patented Aug. 10, 1948 UNITED STATES ELECTROMETER VACUUM TUBE Auguste Louis Marie Antoine Rouy, New York, N. Y., assignor to L. L. H. Company, Erie, Pa., a partnership comprising Hugh 0. Lord, Thomas Lord, and Blanche M. Hartman Application December 22, 1944, Serial No. 569,403

6 Claims. (01. 250-275) My invention relates broadly to electrometer is a transverse sectional view taken on line 3-3 vacuum tubes and more particularly to an imof Fig, 1; and Fig. 4 is atheoretical view illustratproved construction of highly sensitive electroming the effect of the shield in the electrometer eter vacuum tube. vacuum tube of my invention in effecting mutual This application is a continuation-in-part of 5 cancellation of electron and ion charges upon the my application Serial No. 552,892 filed Septemsurface of the shield in the electrometer vacuum her 6, 1944, for Electrometer vacuum tube. tube.

One of the objects of my invention is to pro- In my co-pending application 552,892, supra, I

vide an improved construction of electrometer have explained the functions of an electrometer vacuum tube having means for increasing the to vacuum tube in the measurement of very small sensitivity of the electrometer tube. currents or voltages where the total amount of Another object of my invention is to provide a energy is extremely low such as, for instance, in construction of electrometer vacuum tube conthe case of voltages produced by pressure on a taining control grid, cathode and anode elecpiezo electric quartz crystal cell. I have pointed trodes containing means for effecting mutual out that it is of the utmost importance to avoid cancellation of electron and ion charges upon any losses of the minute charge delivered to the the surface of a shield surrounding the control control grid of the electrometer vacuum tube. I grid. have discovered that the sensitivity of the elec- Still another object of my invention is to protrometer vacuum tube of my invention as set vide an improved construction of electrometer forth in applicati 55 .8 Supra. y be sub vacuum tube containing a control grid, a cathode stantially increased by protecting the control grid system and an anode electrode with a shield of of the e ect ometer tube against y bombarddielectrlc material interposed between the conment by electrons released from the cathode systrol grid and the cathode system for preventing term or against the attachment of any positive electrons from the cathode system from bomions liberated by the electronic bombardment of barding the control grid. the anode. To effect cancellation of such elec- Still another object of my invention is to protrons and ion charg wit spe t to the control vide a construction of electrometer vacuum tube g d, I v de a Cyhnder of q a glass spaced including a control grid, a. cathode system and th sp t to t e Control grid a d a ra e to an anode electrode with a shield of dielectric enclose the control grid for obstructing the conmaterial interposed between the control grid and trol grid against any b rdment by electrons cathode system for preventin any positive ions emanating from the cathode system and at the which are liberated by electrical bombardment S e e preventing e attachment to t e 00 of the anode from reaching the control grid. trol grid of any positive ions which are liberated Still another object of my invention is to proy t electronic bombardment f the anode. vide a construction of quartz or glass shield for The s i ions. a d the tr ns arrying a the control grid of an electrometer vacuum tube, negative charge of electricity fall upon the outer including acontrol grid, cathode system and ansurface of the glass or quartz tube and their ode, which allows acceleration of electrons from e a electrical Charges ancel each other on the cathode system toward the anode through the surface of t e glass or quartz tube. However,

the field created by Voltage applied to th grid the acceleration of electrons from the cathode While obstructing the flow of electrons from the system t ward th an d th u h th field crecathode system to the grid and preventin the ated by the voltage applied to the control grid attachment upon the grid of ions liberated by is not affected by the presence of the glass or the electron bombardment of the anode. quartz screen. The grid current of the electrom- Other and further objects of my invention reeter tube is thus maintained absolutely negligiside in the improved construction of electromble regardless of the voltage applied to the coneter vacuum tube as set forth more fully in the trol grid for thus increasing the sensitivity of the specification herein-after following by reference electrometer vacuum tube for operation under to the accompanying drawings in which: contro1 of the voltages applied to the control grid.

Figure 1 is a vertical sectional view taken Referring to the drawings in detail the electhrough the electrometer vacuum tube of my intrometer vacuum tube is represented as enclosed vention showing the quartz or glass shield enby an envelope I which may be formed in two closing the control grid; Fig. 2 is a transverse secparts having relatively wide flanges 2 and 3 abuttional view taken on line 2-2 of Fig. 1; Fig. 3 ting face to face and serving as supports for the ring member H and project radially, inwardly.

and serve as cantilever supports for the upper ends of filaments l'l, I8 and 19' constituting the; cathode system. The lower ends of the filaments ll, l8 and (9 are supported-bythetripod member 20 which projects through theendof' the envelope of the electrometerivacuum-tube and terminates at 2! forming an electrical connection for the cathode system. The opposite electrical connection. for the cathode system is made to radially extending 'memberfl or. any zother of the supporting rods that connect to the ringmember' H. Thus the cathodesystem is-maintained taut under the action of the spring arms I4,- l and. is as the filaments are heated.

The control grid for the electrometer vacuum tube is represented at 22 entering the envelope of the electrometer Vacuum tube throughthe end as represented at 23 and extending axially of the tube and centrally with respect to the cathode system'forrned by filaments I'l, l8 and I9 and cylindrical anode l.

The's'hield of my invention'consists of a glass or quartz tube 24 which incloses the control grid 22 and extends thereover in'spaced relation with respect thereto. The glass or quartz tube 24 has-one end thereof flanged as represented at 25 within which ring member 26 is embedded. Ring member 26 serves as a'mechanical support for the relatively fragile glass or quartz tube 24. The ring member 25 is supported with respect to ring member H through arm 21 which extends radially to ring ll introducing suificient flexibility into the support to prevent 'shattering'oi the quartz or the glass tube 24 under conditioner shock vibration. The ring member 26 is normally supported out of the plane of ring member I l ailowlng suificient displacement between the end 22a of grid .22 and the closed end 24a of tube 24 to prevent breakage of the shield .24 under 'condition of vibration.

As illustratedin Fig. 4 the electrons emanating from the filaments of the cathode system shown at H, l8 and ii are collected by anode 1,

but are prevented from bombarding control grid 22 by the interposition of the dielectric. shield 25. I have represented a path of electrons from filament 9 at 28, for example, being. deflected at 29 by shield 25 anddirected toward the anode.

l at 38. Ions liberated by bombardment of the anode 1 may take a path, for example, .as representedat 3!, but because of the interposition .of dielectric surface 24 the ions are prevented from reaching control grid 22. electrons and ion charges upon the surface of shield 24 is effected, thus preventing increase in grid current. The grid current is maintained absolutely negligible regardless ofthe voltage applied to the grid and the sensitivity and. eficiency of the electrometer tube increased.

While I havev described'my invention. in one of its preferred embodiments I realize that modiiications may .be made and I desire that 'it be understood that no limitations upon mycinven- Mutual cancellation of 4 tion are intended except as may be imposed by the scope of the appended claims.

What I claim and desire to secure by Letters Patent of the United States is as follows:

1. An electrometer tube comprising an envelope enclosing a, control grid, a cathode system, and an: anode, a shield of dielectric material surrounding said control grid and interposed between said control grid and said cathode system and means resiliently suspending said shield within said envelope in spacial relation to the control grid interiorly of said shield and in spacial relation to said cathode system exteriorly of said shield.

2; An electrometer tube comprising an envelope enclosing a control grid, a cathode system, and

an anode, a quartz shield surrounding said control grid and interposed between said control grid and said cathode system and means resiliently suspending said shield within said envelope in spacial relation to the control grid interiorly of said shield and in spacial relation to said cathode system exteriorly of said shield.

3. An electrometer tube comprising an envelope enclosing a control grid, a cathode system, and

anode, supporting means for said cathode system Within said envelope, a tube of dielectric material surrounding said control grid and spacially related thereto and disposed between said cathode system and said control grid, and means connected with said supporting means and resiliently suspending said tube of dielectric material formovement under conditions of shock vibration without abutment with said control gridor said cathode system.

4-. An electrometer tube comprising an envelope enclosing a control grid, a cathode system,. and an anode, a tubular member of dielectric material surrounding said control grid and interposeddn spacial relation between said control grid and said cathode system for shielding said control grid against bombardment of electrons from said cathode system and from ions liberated by electronic bombardment of said anode, and means supporting said tubular member for axial or transverse .movement with respect to said control grid.

5. An electron discharge device comprising an enclosing vessel, a grid electrode supported axially withinasaid vessel, a cylindrical anode electrode surrounding said grid electrode, a ring-like member concentrically disposed with respect to said gridelectrode and spaced from both said grid and anode electrodes, a multiplicity of filament electrodes supported by said ring-like member and extending in equidistant positions between said grid and anode electrodes, means supporting said ring-dike member and said anode electrode for minimizing displacement of said electrodes under conditions of vibration whereby such displacement of said electrodes which may occur takes place in the same direction, a dielectric shield surrounding said grid electrode and interposed between said grid electrode and said filament electrodes, said dielectric shield being spacially related with respect to both said grid electrode and said filament electrodes and means extending irorntsaid ring-like member supporting said dielectric shield subject to displacement under conditions of vibration without abutment with either said grid or filament electrodes.

6. An electron discharge device comprising an encloslng'vessel, a grid electrode supported axially withinisaid vessel, a cylindrical anode electrode surrounding'said grid electrode, a ring-like member, concentrically disposed with respect to said anode electrode and disposed in spaced relation with respect to one end of said anode electrode, resilient supports extending radially inward from said ring-like member to equidistant positions intermediate said grid and anode electrodes, filament electrodes carried by said resilient supports, means supporting said ring-like member and said anode electrode through the walls of said enclosing vessel for minimizing relative displacement of said filament and anode electrodes under conditions of vibration, and a tubular member of dielectric material surrounding said grid electrode and disposed in spacial relation with respect to said grid electrode and said filament electrodes and supported at one end thereof from said ringlike member whereby said tubular member of dielectric material is displaceable longitudinally and transversely under condition of vibration without abutting with either said grid or filament electrodes.

AUGUSTE LOUIS MARIE ANTOINE ROUY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,291,441 Donle Jan. 14, 1919 1,464,104 Nicolson Aug. '7, 1923 1,619,318 Summers Mar. 1, 1927 1,803,850 Hochstetter May 5, 1931 1,991,632 Scofield Feb. 19, 1935 FOREIGN PATENTS 15 Number Country Date 725,362 France Feb. 12, 1932

Images