US2499546A - Device for making short-time exposures by means of x-rays - Google Patents

Device for making short-time exposures by means of x-rays Download PDF

Info

Publication number
US2499546A
US2499546A US685153A US68515346A US2499546A US 2499546 A US2499546 A US 2499546A US 685153 A US685153 A US 685153A US 68515346 A US68515346 A US 68515346A US 2499546 A US2499546 A US 2499546A
Authority
US
United States
Prior art keywords
voltage
tube
current
rays
ray tube
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US685153A
Other languages
English (en)
Inventor
Vingerhoets Antonius Wilhelmus
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hartford National Bank and Trust Co
Original Assignee
Hartford National Bank and Trust Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hartford National Bank and Trust Co filed Critical Hartford National Bank and Trust Co
Application granted granted Critical
Publication of US2499546A publication Critical patent/US2499546A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08—Electrical details

Definitions

  • the tube When for the operation of the X-ray tube during short periods, use is made of pulsating direct current, the tube is subjected to the full load only during part of every half-wave of the rectified voltage. Besides, the results of the X-ray exposure are dependent, to an appreciable proportion, upon the course of the voltage applied to the tube when loaded, which voltage determines the contrast efiect in the photographic material. .If
  • the voltage is excessively high, the rays are too hard and an insufficient contrast efiect is obtained. If on the contrary, the voltage is excessively low, an appreciable proportion of the rays is absorbed by the body to be radiographed. With a pulsating direct-current voltage, the tube voltage is always too low during part of the phase, with the result that only part of the energy supplied to the tube is converted into useful X-rays so that a low efficiency is obtained.
  • a condenser For feeding the X-ray tube of an X-ray apparatus use is often also made of a condenser which, after being charged up to a determined voltage, is caused to discharge through the X-ray The current which, in this case, flows whilst the discharge is of very short duration.
  • Such devices are very suitable for making short- In order to ensure that a the condenser is converted by the X-ray tube into useful X-rays, the condenser must be charged to a higher voltage than is desirable in view of a satisfactory contrast effect of the X-rays. At the start of the discharge the rays are too hard. After the voltage has fallen below a certain value, the Y hardness of the rays is too low.
  • the invention has for its object to effectuate the load on the X-ra tube at a substantially constant voltage. According to the invention, this is possible by varying the selfinduction of the choke coil during the passage of the load current.
  • the desired influence on the magnetisatlon of the iron core may be obtained by providing on the iron core of the choke coil an auxiliary winding through which a Variable current is sent.
  • this current must be directed in such manner that it brings about a magnetic field which is oppositely directed with respect to the field generated by the current in the self-inductance coil.
  • the current must generate a field of the same direction if a decrease of the self-induction is desired.
  • the current variations in the auxiliary winding may be brought about by connectin a source of direct-current voltage of the auxiliary winding via a commutator which is driven in synchronism with the alternating voltage of the supply mains. It is also possible to provide the iron core with an air gap and to make this gap larger or smaller during the operation of the tube.
  • the desired variations of the self-induction may be brought about by connecting a condenser in series with the auxiliary winding and b connecting this combination of elements in parallel with the inductance coil.
  • the course of the discharge current of the condenser which acts as a source of energy for the X-ray tube is in this case suitable for the automatic control of the magnetlsation of the iron core due to the passage of current through the auxiliary winding.
  • the value of the load current is adjusted in such manner that the exposure is made in the shortest possible timein order to ensure that the unsharpness produced when moving objects are radiographed will be as slight as possible.
  • ' current is determined by the load capacity of the tube andin the case of a constant voltage on the tube it may be taken higher than in the case of a greatly varying voltage on the tube.
  • Figure 1 represents some voltage curves of an apparatus connected in circuit as shown in Figure 2 and- Figure 3 represents some voltage CllIV6S,'f0l a device of which a simplified diagram of connections is shown in Figure 4 and in which the X-ray tube is supplied from a charged condenser.
  • Fig. 5 shows a commutator arrangement for varying the self-inductance of the inductor and Fig. 6 shows a core for the inductor with a variable air-gap.
  • the course ,of the voltage on the X-ray tube is represented by a curve I if, according to Figure 2, the supply device is constituted by a high-voltage transformer M and the current is converted by a rectifying device, for example a discharge tube l5, into a rectified alternating'curre'nt, an inductance coil I! being con- .nected in series with an X-ray tube 6.
  • a rectifying device for example a discharge tube l5
  • the portion a of the curve, wherein the voltage is negative is produced due to the switching-on phenomena which occur in such a device when the load circuit is closed, which may be effected by means of a switch I8.
  • the portion b has a substantially normal, sinusoidal course.
  • auxiliary winding l9 On the iron core of the inductance coil I1 is provided an auxiliary winding l9 through which passes a variable current which is provided by a source of direct current 20 and which is supplied to the winding i 9 via a commutating device 2
  • the self-induction of coil I? can be varied by varying the reluctance of the core, i. e. by employing with a variable air-gap as shown in Fig. ,6.
  • the self-induction of the coil may be given a low value by magnetising the iron core with the aid of a direct current sent through the auxiliary winding 1.9,.
  • the voltage on the tube then increases rapidly to the operation value.
  • the control of the self-induction which is low in the beginning must be large in a portion of. the voltage curve I), in which the voltage submitting the current in the auxiliary winding i9 to determined variations with the aid of a commutator 2
  • the voltage on the tube has in this case the course indicated in the figure by d.
  • the invention aims at obtaining a voltage which is constant over the greatest possible portion of the load and which is denoted in Figure 1 by e.
  • th current control in the auxiliary winding becomes somewhat more complicated, but nevertheless it is still practicable.
  • Owing to the control of the self-induction it is achieved that of the excessive energy provided by the supply device at the voltage which exceeds the operation value, a larger portion is absorbed by the impedance than if this control were not utilized.
  • a larger portion of the energy absorbed by the impedance is delivered to the X-ray tube than in case of the self-induction remaining constant, said portion being larger according as the self-induction is smaller.
  • Figure 3 shows three curves 4, 5 and 6 which represent the course of the voltage in the case of a .device comprising a charged condenser for operating the X-ray tube.
  • the course of the voltage may approximately correspond to curve ,5.
  • the voltage increases rapidly to the value e3, at which the 'X-ray tube begins to yield useful rays. It retains a value in the useful range of the condenser discharge; the generation of active rays terminates after the value eg has been attained again.
  • .It may ,be seen from the figure that in both cases only part of the energy accumulated in.
  • the condenser is efiiciently utilized.
  • An appreciable portion of the total charge is lost and is converted in the X-ray tube into heat unless a device is provided by which the circuit is interrupted immediately after the voltage on the tube has dropped to the value es.
  • the measures required therefor involve a complication, due to which the simplicity of the apparatus and consequently the advantages with respect to devices wherein measures are taken to reduce the loading period are lost.
  • the invention renders it possible to take greater advantage of the energy accumulated in the condenser.
  • the self-induction of the impedance l3 connected in series with the X-ray tube varies automatically during the discharge of the condenser l which acts as a source of supply for the X-ray tube 8.
  • the flow of the discharge current through the X-ray tube can be effected with the aid of a switch which may, for example, be constituted by an electron discharge tube having a control grid.
  • the passage of current through the inductance coil 9 brings about at the terminals of the coil a potential difference which acts upon the passage of current through the auxiliary winding l I which is provided on the iron core 13 of the impedance and whose field also determines the magnetisation of the iron core which is brought about by the field of the coil 9.
  • a condenser l2 in series with the auxiliary winding H the current flowing through the auxiliary winding acquires such a course that the production thereof causes variations of the self-induction of the iron-cored coil in a sense which is favourable for the suppression of deviations from the operation value of the tube voltage.
  • the difference in the voltages set up on the X-ray tube appears from Figure 3 in which the voltage curves approximately represent the average course of the voltage on the tube.
  • the curve 5 represents the voltage in the case of the use of inductance coil in the discharge circuit of the condenser.
  • the curve 6 represents the same voltage in case the invention is carried into effect. No useful radiation is obtained in the one case during the period of time from to to it and in the other case during the period of time from to to 281 since the voltage on the X-ray tube is less than the value 63 and consequently is too low.
  • the period of time from to to h may be considerably shorter than that from to to ft. The loss of energy at the start of the discharge is accordingly smaller.
  • the curve 6 has dropped to the value 63 at a later moment t2 than the curve 3. Due to the greater consumption of energy during the useful load the voltage on the X-ray tube then decreases rapidly. According to curve 6 a greater portion of the available energy than according to curve 5 is consequently consumed in the range in which the voltage has a favourable value. If a determined loading period is desired, the capacity of the condenser which provides the load current may be taken lower by carrying out the invention. If, for example, a capacity of 0.6 1. is used, the self-induction may amount to approximately 1000 henries.
  • the device required for charging the condenser is not shown in Figure 3. It may be realized exactly according to the circuit-arrangements known for this purpose, wherein the charging current is provided by a high-voltage transformer and is supplied to the condenser via a rectifier.
  • the condenser instead of the condenser, use may also be made of a battery of plurality of condensers, whilst the rectifier may consist of one or more discharge tubes or of rectifying devices of other types, such as selenium cells.
  • the charging current may be chosen in such manner that the absorption of energy by the condenser is distributed over a number of waves of the alternating voltage.
  • the switching device in the discharge circuit may, however, also be coupled with an interrupter of the primary current of a highvoltage transformer, in which case the source of charging current is separated from the supply mains at the same moment when the discharge is switched-in.
  • a circuit arrangement for energizing an X-ray tube for a short-time exposure comprising a charge capacitor source of high tension potential for the tube and an iron cored inductance element in series with the capacitor and the tube for supplying substantially constant voltage thereto during an X-ray exposure, the iron cored inductance element including a main winding in series with the capacitor and the tube and an auxiliary winding in series with a source of unidirectional current of variable potential connected in parallel with said main winding for varying the self-inductance of the iron cored inductance element during the discharge of said capacitor source when said tube is being energized to maintain the voltage applied to the tube substantially constant.
  • a circuit arrangement for energizing an X-ray tube for a short-time exposure comprising a charged capacitor source of high tension potential for the tube and an iron cored inductance element in series with the capacitor and the tube for supplying substantially constant voltage thereto during an X-ray exposure, the iron core inductance element including a main winding in series with the capacitor and the tube and an auxiliary winding in series with a second charged capacitor connected in parallel with the main winding for varying the self-inductance of the iron cored inductance element during the discharge of said capacitor source when said tube is being energized to maintain the voltage applied to the tube substantially constant.

Landscapes

  • X-Ray Techniques (AREA)
US685153A 1943-05-21 1946-07-20 Device for making short-time exposures by means of x-rays Expired - Lifetime US2499546A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL632308X 1943-05-21

Publications (1)

Publication Number Publication Date
US2499546A true US2499546A (en) 1950-03-07

Family

ID=19788772

Family Applications (1)

Application Number Title Priority Date Filing Date
US685153A Expired - Lifetime US2499546A (en) 1943-05-21 1946-07-20 Device for making short-time exposures by means of x-rays

Country Status (4)

Country Link
US (1) US2499546A (de)
CH (1) CH258429A (de)
FR (1) FR904462A (de)
GB (1) GB632308A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3217163A (en) * 1962-04-30 1965-11-09 Clevite Corp Piezoelectrically powered x-ray equipment
CN102740579A (zh) * 2011-04-15 2012-10-17 通用电气公司 紧凑型辐射发生器

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2214871A (en) * 1938-08-27 1940-09-17 Gen Electric Voltage generating apparatus
US2222536A (en) * 1937-05-24 1940-11-19 Hartford Nat Bank & Trust Co X-ray apparatus
US2356621A (en) * 1940-06-04 1944-08-22 Welding Research Inc Process and machine for welding by electromagnetic storage of energy
US2416718A (en) * 1942-10-01 1947-03-04 Bell Telephone Labor Inc Pulse generator

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2222536A (en) * 1937-05-24 1940-11-19 Hartford Nat Bank & Trust Co X-ray apparatus
US2214871A (en) * 1938-08-27 1940-09-17 Gen Electric Voltage generating apparatus
US2356621A (en) * 1940-06-04 1944-08-22 Welding Research Inc Process and machine for welding by electromagnetic storage of energy
US2416718A (en) * 1942-10-01 1947-03-04 Bell Telephone Labor Inc Pulse generator

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3217163A (en) * 1962-04-30 1965-11-09 Clevite Corp Piezoelectrically powered x-ray equipment
CN102740579A (zh) * 2011-04-15 2012-10-17 通用电气公司 紧凑型辐射发生器
CN102740579B (zh) * 2011-04-15 2016-12-14 通用电气公司 紧凑型辐射发生器

Also Published As

Publication number Publication date
CH258429A (de) 1948-11-30
FR904462A (fr) 1945-11-07
GB632308A (en) 1949-11-21

Similar Documents

Publication Publication Date Title
US2212217A (en) Oscillatory electric circuits
US4221968A (en) X-Ray diagnostic generator comprising an inverter supplying the high voltage transformer
US2054496A (en) Power control circuits
US3320477A (en) Power supply having over-voltage and over-current protection means
US3103591A (en) Radiographic systems and method
US2499546A (en) Device for making short-time exposures by means of x-rays
US2962594A (en) X-ray apparatus
US2045034A (en) Device for heating incandescible cathodes
US3511996A (en) X-ray generator having means for preventing d.c. magnetization of the transformer core
US2359178A (en) Welding system
US3723798A (en) Traveling wave tube power supply
US2431902A (en) Self-regulating high-frequency generator
US2240037A (en) Method and apparatus for producing x-ray flashes
US2222536A (en) X-ray apparatus
US3873883A (en) Positive ignition power supply for a magnetron
US2700093A (en) Induction heating
US2024333A (en) X-ray installation
US2310742A (en) Transformer
US2359144A (en) Vapor-electric device
US2593845A (en) Apparatus for the acceleration of electrons
US4209406A (en) X-ray diagnostic generator
US3383583A (en) Device for automatic field control in synchronous generators
US1550507A (en) X-ray apparatus
US2930962A (en) Choke input power supplies
US1995176A (en) Electric discharge apparatus