US1961702A - Method and means for the excitation of x-ray tubes - Google Patents

Description

June 5, 1934. M o so 1,961,702

METHOD AND MEANS FOR THE EXCITATION OF X-RAY TUBES Filed April 27, 1931 ATTORNEY Patented June 5, 1934 UNITED S PATENT oFF-ics poration of Delaware Application April 27, 1931, serial No. 533,079

' 3 Claims.

companies varies in different sections of the country. The present trend, however, of these companies is to standardize on'60 cycle current and throughout my specification and claims I will refer to 60 cycles as standard frequency. This variation in frequency presents ever perplexing problems to manufacturers of electrical apparatus and this isparticularly true in the X-ray art. 'As'an example of one of these prob- Iems, the thermionic cathodesof X#ray and rectifier tubes, when constructedfor operation on say cycle current will not operate successfully on '60 cycle current, due to the cooling of' these heavier filaments during operation of the tube. The converse condition is likewise exceedingly unsuccessful due to overheating of the cathodes and the shortening of the life of the tube.

It is, thereforaan object of'my invention to provide an X-ray system in which a thermionic discharge device is utilized wherein electrical energy of one frequency may be impressed upon'the electrodes of the device and electrical energy of a different frequency may be utilized to heat the cathode of the device.

Another object of'my invention is the provisionof an X-ray system in which electrical energy of one frequency may be utilized to energize the electrodes'of an X-ray or rectifier tube and electrical energy of another frequency may be utilized for heating the cathodes thereof.

"Another objectof my inventionis the provision of an X-ray system in which electrical energy of one frequency may be utilized to energize the electrodes of an X-ray and rectifier tube and electrical energy of the same or a different frequency may beutilized'for heating thecathodes'thereof as desired. I

A further object of my invention is the provision of an X-ray circuit in which an X-ray tube designed for operation on currents of one frequency may be successfully utilized with a thermionic rectifier tube designed for operation on currents of a different frequency.

Still further objects of my invention will become apparent to those skilled in the art by reference to the accompanying drawing wherein the by'the motor. A pair of conductors 16 and 17 extend'from'this standard frequencey generator 14 'tothepri'mary winding 18 of a low tensiontr-ans single figure is a diagrammatical representation of an X-ray circuit embodying the details of construction and arrangement of the various parts in accordance with my invention.

Referring now to the drawing in detail I hat/e6 shown a generator 5 for generating electrical energy of the usual commercial alternating current potential of 25 cycles per second and I shall refer to this as a low frequency or less than standard frequency source. A pair of supply conductors 6 and 7 extend from this generator and'are connected to the primary winding 8 of a high-tension transformer 9.

A hand operated switch 10 is provided in the conductor 7 for opening and closing the circuit from the source 5 to the primary winding 8. The

conductors 6 and 7 also extend to'a small syn- 'electricalenergy'such as a battery 13.

A small alternating current generator 14 of commercial potential and of standard 60 cycle frequency is coupled to the synchronous motor 12 by means of a shaft 15 and is thus driven former 19 for the purpose of energizing the latter. A pair of conductors 2i) and 22 are connected to the low frequency conductors 6 and '7 and extend to two terminals 23 and 24 of a double-pole double-throw switch 25.

Another pair of conductors 26 and 27 are connected to the conductors 16 and 1'7 from the standard frequency source 14' and extend to two contact terminals 28 and 29 of the switch 25. The primary winding 30 of a low'tension transformer 32 is connected by means of a pair of conductors 33 and 34 to the center of blades 35 and 36 of the switch 25. In this manner, when the switch is in a position in which the blades 35 and 36 are in'contactwith the terminals 23 and 24, the primary winding 30 is connected to the low-frequency source 5, and when the blades 35 and 36 v are in contact with the terminals 28 and 29 the primary winding 30 is connected to the standard frequencysource 14.

A thermionic rectifier tube 37, is arranged to have its cathode heated from the secondary wind- I ing 38, of the low-tension transformer 19 through conductors 39 and 40, and an X-ray tube 42, likewise receives heating currents for its cathode from a secondary winding 43 by means of conductors 44 and 45 which extend from the low tension transformer 32. A conductor 46 extends from the anode of the X-ray tube 42 to one end of the secondary winding 47 of high-tension transformer 9 and the other end of the secondary winding 47 is connected by means of a conductor 48 to the conductor 39 leading to the rectifier tube 3'7. The anode of the rectifier tube 3'7 is connected by means of a conductor 49 to the conductor 44 leading to the cathode of the X-ray tube 42.

The X-ray tube 42 may be a tube designed for operation on currents of less than standard frequency or on standard frequency currents. Ths rectifier tube 37 is designed to have its cathode heated by currents from a standard frequency source and currents of less than standard frequency may be impressed across the electrodes of the rectifier tube. In this manner discharge tubes of standard manufacture may be utilized on commercial alternating current lines wherein the frequency is less than standard or 60 cycle.

The operation of my device is as follows: the synchronous motor 12 is connected to the lowfrequency source and is excited from the direct current source 13. This motor in turn drives the standard frequency generator 14 through the shaft 15. The switch 10 is closed allowing the primary winding 8 of high tension transformer 9 to become energized and the primary winding 18 of the low tension transformer 19 is energized from the generator 14.

The double pole switch 25 is then closed establishing contact between the blades 35 and 36, and the contact terminals 23 and 24 which energizes the primary winding 30 from the lowfrequency source 5 by means of the conductors 20 and 22. Energization of the primary windings 18 and 30 of low tension transformers 19 and 32 respectively, energizes the secondary windings 38 and 43 of these transformers and thus heats the cathodes of the rectifier tube 37 and X-ray tube 42.

The closing of the switch 10 and the resulting energization of transformer 9 causes high-potential energy to fiow from the secondary winding 47 by means of conductor 48, rectifier tube 3'7, conductor 49, X-ray tube 42, and thence over conductor 46 back to the secondary winding 47. This circuit is completed and high-potential currents will flow during each half-wave of the alternating current cycle in the manner just described and during the remaining half-wave current will be prevented from flowing by means of the valve action of the rectified tube 37.

Should it be desired to energize the cathode of the X-ray tube 42 from a standard frequency source instead of from the source of less than standard frequency the switch 25 is merely changed into contact with the terminals 28 and 29. This enables standard frequency currents to fiow from the source 14 by means of conductors 16, 1'7 and 26, 2'7 and energize the primary winding 30 of low-tension transformer 32 which in turn heats the cathode of X-ray tube 42 with standard frequency currents.

It can thus be readily seen by those skilled in the art that I have provided an X-ray system in which thermionic discharge tubes may be readily utilized in which currents of less than standard frequency may be impressed upon the electrodes of the tubes and currents of standard frequency be utilized to heat the cathodes of these tubes. This system permits the employment of tubes of standard frequencies which are readily adaptable uniformly to all sections of the country regardless of variation in frequencies in different sections.

What is claimed is:

1. In an X-ray system, an X-ray tube provided with a cathode to be heated, a high-tension transformer for supplying energy to said X-ray tube, a low-tension transformer for supplying heating current to the cathode of said X-ray tube, a source of electrical energy of a given frequency common to the primary windings of both said transformers for energizing the same, a thermionic discharge device provided with a cathode to be heated and connected in a circuit with said Y-ray tube and said high tension-transformer, means connected to said source of electrical energy for generating electrical energy of a frequency different from that of said first mentioned source, and a lowtension transformer connected to said means for supplying heating current to the cathode of said discharge device.

2. In an X-ray system, an X-ray tube provided with a cathode to be heated, a high-tension transformer for supplying energy to said X-ray tube, a low-tension transformer for supplying heating current to the cathode of said X-ray tube, a source of electrical energy of less than standard frequency common to the primary windings of both of said transformers for energizing the same, a thermionic discharge device provided with a cathode to be heated and connected in a circuit with said X-ray tube and said high-tension transformer, means connected to said source of electrical energy for generating electrical energy of a standard frequency, a low-tension transformer connected to said source of standard frequency for supplying heating current to the cathode of said discharge device, and means for disconnecting said first mentioned low-tension transformer from said source of less than standard frequency and connecting the same to said source of standard frequency if desired.

3. In an X-ray system, an X-ray tube provided with a cathode to be heated, a high-tension transformer for supplying energy to said X-ray tube, a low-tension transformer for supplying heating current to the cathode of said X-ray tube, a source of electrical energy of less than standard frequency common to the primary windings of both said transformers for energizing the same, a thermionic discharge device provided with a cathode to be heated and connected in a circuit with said X-ray tube and said high-tension transformer, a synchronous motor connected to said source of less than standard frequency, a standard frequency generator coupled to said synchronous motor, and a low-tension transformer connected to said standard frequency generator for supplying heating current to the cathode of said thermionic discharge device.

MONTFORD MORRISON.

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