US1999736A - Discharge device stabilizer system - Google Patents

Description

April 30, 1935@ M. MORRISON DISCHARGE DEVICE STABILIZER SYSTEM Filed July 10, 1931 INVENTOR MONT/CORD MORE/50 BY 2% 9 .9 ATTORNEY UNITED STATES PATENT OFFICE DISCHARGE DEVICE STABILIZER SYSTEM 7 Montford Morrison, Montclair, N. J., assignor to Westinghouse X-Ray Company, Inc., a corporation of Delaware Application July 10, 1931, Serial No. 549,831

4 Claims.

My invention relates to stabilizer systems and has particular relation to a sy stem for maintain- I ing the currentfiowing through a thermionic discharge device constant irrespective of fluctuations in the source of energy and constitutes an improvement of the system shown'and described in my Patent No. 1,616,702 issued February 8,

In the operation of thermi vices it is well known to the stancy of the current flowing trodes of the device is dependent upon numerous factors, such for example as onic discharge deart that the conbetween the electhe degree of vacuum of the device, gaseous ionization within the device and'the temperature of the cathode.

As a system of this general type is usually operated. from a source of commercial alternating current potential which is subject to current fiuctuations, and a low voltage from this source is utilized to heat the thermionic cathode erratic flow of discharge current results upon a variation in any of the above mentioned factors.

In order to maintain the discharge current constant the electron emissivity must be maintained constant. In the prior art stabilizing systems have been employed, but such systems are usually directed tovarying the electron emissivity of the cathode. rent supplied to the cathode tions in the source of supply temperature of the cathode.

This is accomplished by varying the curinversely to variathus changing the In my prior patent hereinbefore mentioned I have stated that the most important use of a device of the character therein shown and described was the elimination of erratic behavior in the discharge device irrespective of the factor to which erratic flow could be attributed.

discharge device inversely to source of supply if desired.

Still further objects of my variations in the invention will become apparent to those skilled in the art by reference to the accompanying drawing wherein the single figure is a diagrammatic representation of a system employing the novel features of my present invention.

Referring now to the drawing in detailI have shown a source of commercial alternating current potential, such as conductors LI and. L2. A pair of conductors 6 and I extend from this source to the primary winding 8 of a low tension transformer 9, and a variable resistance Ill is interposed in the conductor 7 for varying the current supplied to the primary winding 8 from the source.-

The secondary winding [2 of the low tension transformer 9 is arranged to supply heating current to the cathode l3 of a thermionic discharge device, such as an X-ray tube M, by means of a pair of conductors l5 and 16. A high tension transformer ll likewise has its primary winding 48 connected to the source of supply by means of a pair of conductors l9 and 20.

A pair of high tension conductors 22 and 23 connect the secondary winding 24 of the high tension transformer with terminals 25 and 26 of a mechanical rectifier 21. This rectifier is provided with a pair of toroidal surfaces 28 and 29 and is rotated by means of a synchronous motor (not shown) which may be connected to the supply source Li and L2 in a well known manner for the purpose of causing the current from the secondary winding to flow in one direction during the entire alternating current cycle.

A terminal 36 of the rectifier device is connected, by means of a conductor 32, to the anode 33 of the discharge device l4 and is arranged during operation of said device to suppy positive potential thereto. Another terminal 34 of the rectifier supplies negative potential through a conductor 36, to a junction as in the conductor l5 and thus supplies negative potential to the cathode 53 of the X-ray tube.

The primary winding 8 of the low tension transformer 9 being energized from the source of supply the secondary winding 12 is energized and heats the cathode 13 of the discharge device M. Likewise upon energization of the transformer l "i high tension current will flow from the secondary winding 24 of the high tension transminals 25, 30 and 26, 34 during one-half wave r of the alternating current cycle, and then the respective terminals 25, 34 and 26, 30 during the remaininhalf wave thereof as well known to I the art.

The source of supply LI and L2 being subject to fluctuations these fluctuations will necessarily aifect the secondary winding I2 of the low voltage transformer and the temperature of the cathode l3 will likewise vary causing erratic flow in the high tension or discharge circuit.

In order to maintain the temperature of the cathode l3 constant by varying the temperature thereof inversely to the supply source fluctuations I provide a pair of tertiary windings 42 and 43 in the iron core of the transformer 9.

It will be noted that the winding 42 is wound upon the core of the transformer 9 differentially to that of the winding 43 which is for a purpose to be hereinafter more fully'described. A conductor 44 is connected to one end of each of the windings 42 and 43 and extends to an anode 45 and cathode 45 respectively of a pair of discharge devices 47 and 43. The cathode 49 of the discharge device 4? is connected, by means of a conductor 55 to the other end of the tertiary winding 42 while a similar conductor 52 extends from the anode 33 of the other discharge device 48 to the other end of the tertiary Winding 43.

Each discharge device is provided with an auxiliary electrode 54 and 54' for the purpose of maintaining a potential upon the device. The electrode 54 of the device 41 is connected, by means of a conductor 55, to a portion of the tertiary winding 42, and the electrode 54' of the other device 48 is similarly connected, by means of a conductor 56, to a portion of the other tertiary winding 43.

A variable condenser 5"! is connected between the conductors 44 and 52 at junctions 58 and 59, in shunt with the winding 43, and a similar condenser til is connected between the conductors 44 and 50 between junctions 59 and 62, in shunt with the winding 42. A conductor 64 extends from the junction 62 to a junction 65 in the conductor 39 and is thus connected to the cathode I 3 of the X-ray tube.

These discharge devices 4i and 48 are of a type well known to the art as having a critical breakdown characteristic. In operation a potential is normally applied between the auxiliary electrode and the anode which is of an insuflicient value to ionize the gas within the tube. When, however, the potential rises above the critical breakdown value gaseous ionization results and permits a current to flow between the cathode and anode of the device.

Assuming now that current is flowing through the discharge device or X-ray tube 84 in the manner previously described and that the transformer 9 is supplying heating current to the oathode of the X-ray tube, a potential will be induced in the tertiary windings 42 and 43 by the primary Winding 8 of transformer 9. When the induced voltage in the windings 42 and 43 from the source or primary winding 8 is below the critical breakdown value of the discharge devices 41 and 48 the circuits associated therewith and these windings have no effect upon the secondary winding l2 and consequently the cathode l3 as the-magnetic flux of the transformer 9 is unaltered.

During alternate half waves of the alternating current cycle when, due to fluctuations in the source LI and L2, the induced potential in the windings 42 and 43 reaches a predetermined value, which is equal to the critical breakdown value of the electrodes 54, 45 and 53, 54 of the respective discharge devices 4'! and 48, a current will flow through the windings 42 and 43. For example, during one-half wave if the potential induced in the winding 42 reaches the breakdown value of discharge device 41 a current will flow from the winding 42, through conductor 50, to the cathode 49, thence to the anode 45 back to the winding 42 by means of conductor 44. Similarly during the remaining half wave if the induced potential is high enough a current will flow from the winding 43, through conductor 44 to the cathode 46 of the other discharge device 48, thence to the anode 53 and back to winding 43 by means of conductor 52. Accordingly this flow of current through either of the windings 42 or 43, upon an increase in the induced potential changes the magnetic flux of the transformer 9 which reduces the current supplied by the secondary winding l2 and consequently reduces the temperature of the oath- .0de 13.

Moreover, the voltage at which breakdown of the discharge devices 4'! and 48 occurs is exceptionally critical. This is due to only a slight increase in the induced potential within the windings 42 and 43 being necessary to initiate a discharge between the auxiliary electrodes 54, 54' and the cathodes 45, 49 respectively. Once the potential of the portions of the windings 42 and 43 reaches a value sufllcient to cause a discharge between the respective auxiliary electrodes and cathodes a main discharge follows between the respective anodes and, cathodes with a flow of current through the entire windings 42 and 43.

nected in a shunt or parallel relation with the tertiary windings 42 and 43, respectively, accordingly become charged by the potential induced by the primary winding 8 until this potential rises to the critical breakdown value of the glow discharge devices 4! and 48. In this manner they more or less regulate the breakdown value of the discharge devices and when charged to the amount at which they arev set they alternately discharge during each half wave of the:

alternating. current cycle through the winding and glow discharge device with which they are connected thus changing. the, magnetic flux of the transformer 3 in the manner previously described.

In reducing the temperature of the cathode it necessarily follows that the electron emissivity of the cathode l3 becomes less thus reducing the current flowing in the discharge or high tension circuit. Ordinarily a simultaneous increase in the discharge circuit and in the temperature of the cathode l3 would occur with an increase of current in the primary winding 8. This would cause the thermionic emissivity of the cathode to increase with an increase of current in the discharge circuit and no stabilization would therefore occur.

.In order to prevent this increase in the discharge circuit, the temperature of the cathode I3 is reduced by the action of the tertiary windings 42 and 43, in the manner previously described. This action varies the temperature of the cathode I3 inversely to the variations in the source and prevents an increase of current in the source from increasing the current in the discharge circuit. In this manner the amount of current flowing through the discharge device !4 is maintained constant" irrespective of the wave form of the potential in the alternating current source of supply.

When the potential in the source again falls below the critical breakdown value of the devices 41 and 48 current will no longer flow through the respective windings 42 and 43. This enables '30 The variable condensers 5! and 60 being conmeat/es the magnetic flux of the transformer 9 to again change and the current in the secondary winding it to increase, thus increasing the temperature of the cathode it. At the same time the potential in the source decreases the amount of potential impressed on the primary winding 8, the amount of current in the discharge circuit also decreases. A decrease, therefore, in the discharge circuit and an increase in temperature, with a resulting increase of electron emissivity, of the cathode allows a constant flow of current through the thermionic device M.

It thus becomes obvious to those skilled in the art that I have provided a stabilizer system for thermionic discharge devices in which the cathode heating current is maintained constant irrespective of fluctuations in the source. Moreover, my entire system is exceptionally critical to very slight fluctuations in the supply source thus effecting a very high degree of stabilization and eificiency.

Although I have shown and described one specific embodiment of my device I do not desire to be limited thereto as various other modifications of the same may be made without departing from the spirit and scope of the appended claims.

1. The combination of an electron chscharge device provided with a cathode to be heated, a high tension transformer for supplying energy to said discharge device, means connected to said high tension transformer and said discharge de ice to cause the current to flow through the latter in one direction only during the entire alternating current cycle, a low tension transformer for supplying heating current to the cathode of said device, a source of alternating current of commercial potential for supplying energy to both of said transformers and subject to variations a potential during operation of said device, and Means connected with said low tension transformer for varying the current supplied thereby to the cathode of said device comprising a plurality of tertiary windings differentially associated with respect to each other, a plurality of circuits each including a glow discharge device having a critical breakdown characteristic and one of said tertiary windings, and operable periodically to cause current flow in each of the respective circuits with a resultant variation in the energy supplied by said low tension transformer to the cathode of first mentioned discharge device inversely to the variation in said commercial suppiy source.

2. The combination of an electron discharge device provided with a cathode to be heated, a low tension transformer connected with said cathode in order to heat said cathode by supplying currents thereto, a high tension transformer connected with said electron discharge device for supplying energy to the latter, means connected to said high tension transformer and said discharge device to cause the current to flow through the latter in one direction only during the entire alternating current cycle, a source of alternating electrical energy of commercial potential connected to both of said transformers for supplying the same with energy and subject to variations during operation of said discharge device at positive and negative half waves of the alternating current cycle, and means to vary the magnetic flux of said low tension transformer to cause an inverse variation in cathode heating current relative to the variations in said alternating source of energy during positive and negative half waves of the latter comprising a pair of tertiary'windings integral with said low tension transformer and differentially wound relative to each other, and a glow discharge device connected to each of said windings having a critical breakdown characteristic and operably responsive, when the variations in said alternating source exceed a predetermined amount, to breakdown and cause current how in the respective winding connected therewith and a resultant variation in the magnetic flux of said low tension transformer.

3. The combination of an electron discharge device provided with a cathode to be heated, a high tension transformer for supplying energy to said discharge device, means connected to said high tension transformer and said discharge device to cause the current to flow through the latter in one direction only during the entire alternating current cycle, a low tension transformer for supplying heating current to the cathode of said device and provided with an iron core subject to magnetic flux during energization of said transformer, a source of alternating current of commercial potential for supplying energy to both of said transformers and subject to current and potential variations during operation of said discharge device, and means connected with said low tension transformer for varying the current supplied thereby to the cathode of said device comprising a plurality of tertiary windings differentiaily wound with respect to each other upon the iron core of said low tension transformer, and a plurality of circuits each including a glow dis charge device having a critical breakdown characteristic and one of said tertiary windings, one of said circuits being operable during positive half cycles of said commercial supply source and the other being operable during the negative half cycles of the latter to cause a variation in the magnetic flux within the core of said low tension transformer with a resultant variation in the energy supplied by said low tension transformer to the cathode of said first mentioned discharge device during the entire cycle of said commercial supply source.

4. The combination of an electron discharge device provided with a cathode to be heated, a high tension transformer for supplying energy to said discharge device, means connected to said high tension transformer and said discharge device to cause the current to iiow through the latter in one direction only during the entire alternating current cycle, a low tension transformer provided with an iron and primary and secondary windings for supplying heating current to the cathode of said device, a source of alternating current of commercial potential for supplying energy to said high tension transformer and to the primary winding of said low tension transformer, and subject to variations in potential during operation of said device, and means for maintaining the energy supplied to said cathode constant during the entire alternating current cycle of said commercial source of supply comprising a tertiary winding wound upon the core of said low tension transformer and energizable by the primary winding thereof, a glow discharge device having a critical breakdown characteristic and provided with an anode connected to one end of said tertiary winding and a cathode connected to the other end of said tertiary winding, said glow discharge device being operable to breakdown during positive half cycles of said commercial supply source when the latter exceeds a predetermined potential, and to cause current flow in said tertiary winding with a resultant variation in the energy supplied by said low tension transformer to the cathode of said electron discharge device inversely to the variations of said commercial supply source, a second. tertiary winding differentially wound upon the core of said low tension transformer with respect to said first mentioned tertiary Winding and energizable by the primary winding thereof, and a second. glow discharge device having a critical breakdown characteristic and provided with an anode connected to one end of said second tertiary winding and. a cathode connected to the other end thereof, said second glow discharge device being operable to breakdown during negative half cycles of said commercial source of supply when the latter exceeds a predetermined potential, and to cause current flow in said second tertiary winding with a resultant variation in the energy supplied by said low tension transformer to the cathode of said electron discharge device inversely to the 10 variations of said commercial supply source.

MONTFORD MORRISON.

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