US2870340A - X-ray tube voltage control circuit - Google Patents

X-ray tube voltage control circuit Download PDF

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Publication number
US2870340A
US2870340A US544514A US54451455A US2870340A US 2870340 A US2870340 A US 2870340A US 544514 A US544514 A US 544514A US 54451455 A US54451455 A US 54451455A US 2870340 A US2870340 A US 2870340A
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United States
Prior art keywords
voltage
tube
transformer
current
ray tube
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Expired - Lifetime
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US544514A
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English (en)
Inventor
Fransen Jacobus
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US Philips Corp
North American Philips Co Inc
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US Philips Corp
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    • 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
    • H05G1/26—Measuring, controlling or protecting
    • H05G1/30—Controlling
    • H05G1/48—Compensating the voltage drop occurring at the instant of switching-on of the apparatus
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current
    • G05F1/12—Regulating voltage or current wherein the variable actually regulated by the final control device is ac
    • G05F1/32—Regulating voltage or current wherein the variable actually regulated by the final control device is ac using magnetic devices having a controllable degree of saturation as final control devices

Definitions

  • FIGJ Volta g X-RAY TUBE 'VOLTAGE CONTROL CIRCUIT Filed Nov. 2, 1955 Ra T2 FIGJ Volta g:
  • Stabilizer t Timer AAA FIG-2 INVENTOR JdcoAuJ Hansen United States Patent X-RAY TUBE VOLTAGE CONTROL CIRCUIT Jacobus Fransen, Eindhoven, Netherlands, assignor, by
  • the present invention relates to an X-ray tube voltage control circuit.
  • X-ray tubes are usually accompanied by one or more regulating devices, for example, a device for selecting the voltage between the anode and the cathode of the X-ray tube (tube voltage) and also a regulating device for adjusting the current which. serves to heat the incandescent cathode of the X-ray tube.
  • the regulating device permits the control of the electron emission in the X-ray tube (tube current).
  • steps are taken to make the tube current independent of the position occupied by the voltage selector. These steps afford the advantage that the different load values may be adjusted more easily in taking X-ray photographs.
  • the charge adjusted by the current regulator and the time selector may be indicated on a reading scale which is usually calibrated in units representing the product of milliamperes and seconds. If the tube current is dependent upon the tube voltage, a difierent milliampere-scale is required for any tube voltage to be selected. If, however, the tube current does not vary as a result of variation in voltage, the same milliampere-scale may serve for any voltage selected.
  • Several means may be utilized to make the tube current independent of the position of the voltage selector. It is possible, for example, to include a variable resistor in the heating-current circuit of the X-ray tube and to couple its regulating member to the regulating member which serves to select the tube voltage. As an alternative, for the same purpose, use is made of a transformer, the primary voltage of which is controlled by means of an operating member coupled to the voltage selector and the secondary winding of which is included in the heatingcurrent circuit. The eliect of such steps is not very accurate as a result of the fact that the tube voltage is determined not only by the position of the voltage selector, but also by the voltage drop across the different resistances, which voltage drop varies with the current strength. Consequently, they can lead to perfect correction only for a predetermined value of the tube current.
  • the X-ray tube is usually accompanied by a graph showing a plurality of curves each corresponding to a predetermined current and indicating the tube voltage asa function of the transformation ratio of the regulating transformer.
  • the graph indicates the position which the voltage selector must occupy to produce a determined tube voltage for a given tube current.
  • An object of the invention is to facilitate the production of the voltage graph and the adjustment of the tube voltage.
  • the X raytube control circuit of the present invention comprises means for insuring that-the voltage drop for any position of the voltage selector is constant for a given value of the tube current.
  • the lines of the voltage graph are straight and the tube voltage for a series of values of the tube current is to be determined in only one position of the voltage selector.
  • the selector for the tube voltage is coupled to a variable resistor included in the supply circuit of the X-ray tube, so that the impedance in this circuit, and hence the voltage drop, varies when the voltage varies.
  • the resistance value required of said resistor is calculated for the various positions of the voltage selector to maintain constancy of the voltage drop, a non-linear relation between the impedance and the transformation ratio of the regulating transformer is found.
  • the control circuit of the present invention may alternatively be designed so that the tube voltage is no longer dependent upon the position of the current regulator. In this case it is no longer necessary to consult a graph, or a table, or to keep in mind a series of correction values, in order to adjust the tubevoltage; the reading scale associated with the member for operating the voltage selector may be provided with a number indicating directly the value of the tube voltage for eac position of said member.
  • an auxiliary voltage is added to the supply voltage for the X-ray tube.
  • the auxiliary voltage is constant for any transformation ratio of the regulatingtransformer, but varies with the tube current. Consequently, it may be chosen by theoperating member of the current regulator.
  • the tube current tion of load so that the tube current decreases with an regulator mayv be coupledin-lknown manner to a timing device for selecting the 'dura-il increase in the duration of load, and conversely. It is thus possible always to obtain automatically the optimum load on the tube and to avoid overload of the tube.
  • Fig. 1 is a schematic diagram of an equivalent circuit of an X-ray tube voltage control circuit
  • Fig. 2 is a schematic diagram of an embodiment of the X-ray tube voltage control circuit of the present invention.
  • v The cause of the vo tage drop and the manner in which its value may be determined, may be observed bv reference to Fig. 1.
  • the regulating transformer which is of the autotransformer type, and the high-tension transformer, are indicated by T and T respectively.
  • the variable transformation ratio of the autotransformer is represented by N and the constant transformation ratio of the high-tension transformer is represented by N
  • the X-ray tube voltage which is obtained when the Xray tube current is switched on, is
  • E is the drop in voltage due to the resistances R,,, R,, and R
  • E is the difference between the no-load tube voltage and the loaded tube voltage
  • the voltage drop may be represented by This comprises two components I (R -l-R N and IR N N
  • the first componentI(R -l-R,,N is not dependent upon the transformation ratio N and the second component IRgN N varies quadratically with N It is to be noted that R actually is slightly dependent upon N However, by suitable adjustment of the resistance steps, erroneous resultant values are avoided.
  • E;,-(IR -l-IR N j-IR N N must be constant.
  • Fig. 2 is a schematic diagram of an embodiment of the X-ray tube voltage control circuit of the present invention.
  • a transformer 1, which is of the autotransformer type, is connected to the power supply terminals via a variable resistor 3.
  • the resistor 3 serves to bring the impedance of the primary circuit of the regulating transformer 1 to that value which is used in calibrating the device or in providing the voltage graph.
  • Said primary circuit also includes a regulator 4 which can connect one of the power supply lines 2 to different tapping points on the winding of the transformer 1.
  • a voltmeter 5 provided between two fixed points of the transformer Winding, to be always adjusted to a prescribed indication irrespective of local variations in the power supply voltage.
  • the heating current for the cathode of the X-ray tube 6 is supplied by a heating-current transformer 7. Since several methods are known for maintaining the tube current constant, upon variation of the tube voltage, it is not necessary to refer thereto in detail. For the sake of completeness, a variable resistor 8 which serves to maintain the tube current constant, is shown in the primary circuit of the heating-current transformer 7. The regulating member of the resistor 8 is coupled to a voltage selector 13.
  • the heating current circuit also includes a voltage stabilizer 9 and a variable resistor tube current regulator 10.
  • the resistor 16 serves to control the tube current.
  • the AC output in the secondary winding of a high tension transformer 12 is rectified by a rectifier bridge 14 and is supplied to the X-ray tube 6.
  • the regulating transformer 1 supplies the supply volage to the high-tension transformer 12.
  • the primary winding of the high tension transformer 12 may be connected, by way of the voltage selector 3, to different tapping points 15 on the winding of the regulating transformer I.
  • the primary circuit of high tension transformer 12 includes a variable resistor 18, the regulating member of which is coupled to the voltage selector 13.
  • the selector 13, the resistor 18 and the resistor 8 are coupled together mechanically, or in another manner, said elements being shown connected together by a dot-and-dash line.
  • the value of the resistor 18 be varied in such a manner that the voltage drop is not affected by this variation in position.
  • the resistance value of the resistor 18 must vary quadratically with the transformation ratio of transformer 1, it has been found that for the comparatively small regulating range commonly used in practice, a linear variation provides sutiiciently accurate approximation.
  • the maximum value of N to which the voltage selector 13 may be adjusted, is usually not higher than thrice the minimum value.
  • the maximum deviation which occurs when the parabolic curve showing the resistor R, as a function of N is substituted by a straight line connecting the extreme points of this curve is not more than 20%.
  • the voltage drop is usually maintained below a reasonable limit by suitable choice of the various resistance values of the circuit and will seldom be more than 25% of the no-load voltage.
  • the core of the regulating transformer 1 carries a separate auxiliary winding 16.
  • the voltage induced in the winding 16 serves to make the voltage drop independent of the position of the regulator for the tube current. Due to the inclusion of the winding 16 in one of the supply lines to the high-tension transformer 12, the voltage induced in said winding constitutes a contribution to the supply voltage of said transformer.
  • the auxiliary voltage E produced in the winding 16 must vary with current.
  • a regulating member 17 which may be connected to different tapping points on the auxiliary winding 16 and which is couped to the regulating member of the resistor as shown by a dot-and-dash line.
  • the regulating steps of the auxiliary winding 16 may best be determined empirically.
  • the supply current of the high-tension transformer 12 (at the beginning and at the end of the duration of load) is switched on and off by means of an electromagnetically operated switch 19.
  • the energizing current of the switch 19 is controlled by a timer 11.
  • the timer 11 may be coupled in known manner to the regulating member of the resistor 10 (as shown by a dot-and-dash line) so that either the X-ray tube is prevented from being loaded more strongly than is permissible for the chosen duration of load, or an optimum load on the X-ray tube is always obtained.
  • variable resistor 18 may alternatively be included in the primary circuit, instead of in the secondary circuit, of the autotrausformer 1.
  • the condition that the regulating characteristic of the resistor theoretically has to satisfy in such a case may be readily determined from the foregoing equations.
  • the auxiliary voltage of the auxiliary winding 16 must vary in proportion with the tube current.
  • An X-ray tube voltage control circuit comprising an X-ray tube having an anode and a cathode, a source of power supply, transformer means having a variabletransformation ratio and being coupled between said supply source and saidanode and cathode of said tube, a selective member for varying the transformation ratio] of said transformer means, variable impedance means having an impedance regulating member, said impedance means being interposed in the supply circuit of the anode between said supply source and said tube, and means for coupling said regulating member to said selective member, said impedance means at a first given position of said selector and regulating member having a value rendering the total voltage drop resulting from the load on the X-ray tube equal to that occurring at a second given position of said selector and regulating member.
  • An X-ray tube voltage control circuit comprising an X-ray tube having an anode and a cathode, a source of power supply, transformer means having a variable transformation ratio and being coupled between said supply source and said anode and cathode of said tube, a selective member for varying the transformation ratio of said transformer means, variable impedance means having an: impedance regulating member, said impedance means being interposed in the supply circuit of the anode between said transformer means and said tube and being variable in steps proportional to those of said transformation ratio, and means for coupling said regulating member to said selective member, said impedance means at a first given position of said selector and regulating member having a value rendering the total voltage drop resulting from the load on the X-ray tube equal to that occurring at a second given position of said selector and regulating member.
  • An X-ray tube voltage control circuit comprising an X-ray tube having an anode and a cathode, a source of power supply, transformer means having a variable transformation ratio and being coupled between said supply source and said anode and cathode of said tube, a selective member for varying the transformation ratio of said transformer means, variable impedance means hav ing an impedance regulating member, said impedance means being interposed in the supply circuit of the anode between said transformer means and said tube and bzing variable in steps having intermediate vaues which are a quadra ic function of said transformation ratio thereby to provide a substantially constant voltage drop through its entire regulating range, and means for coupling said regu ating member to said selective m mber, said imped nce means at a fi st given positi-n of aid sele'tor and regu at ng mem er havin a va'ue rendering the total voltage drop resu ting from the load on he X-ray
  • variable im edance means having an imped nce re ulating member, said im ed nce means bein inter osed in the suoulv circuit of the anode between said tr nsf rmer means and said tube.
  • means for derivin a variable auxiliary volta e fr m said sunplV source said last-mentioned means including a second selective member for varving said auxiliary voltage, means for coupling said regulating member to said first selective member, means for supplying a current to the cathode of said tube including further variable impedance means interposed between said supply source and the said cathode and having an impedance regulating member.
  • An X-ray tube voltage control circuit comprising an X-ray tube having an anode and a cathode, a source of power supply, transformer means having a variable transformation ratio and being coupled between said supply source and said anode and cathode of said tube, a first selective member for varying the transformation ratio of said transformer means, variable impedance means having an impedance regulating member, said impedance means being interposed in the supply circuit of the anode between said transformer means and said tube, means for deriving a variable auxiliary voltage from said supply source, said last-mentioned means including a second selective member for varying said auxiliary voltage, means for coupling said regulating member to said first selective member, means for supplying a current to the cathode of said tube including further variable impedance means interposed between said supply source and the said cathode and having an impedance regulating member, means for coupling the regulating member of said further variable impedance means to said second selective member,
  • timing means and means for coupling said timing means I to the regulating member of said further variable'impedance means whereby the current in the X-ray tube decreases with increasing duration of load on said tube and increases with decreasing duration of load on the said tube.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Automation & Control Theory (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • X-Ray Techniques (AREA)
US544514A 1954-11-03 1955-11-02 X-ray tube voltage control circuit Expired - Lifetime US2870340A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL192086A NL103475C (nl) 1954-11-03 1954-11-03 roentgentoestel

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US2870340A true US2870340A (en) 1959-01-20

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US544514A Expired - Lifetime US2870340A (en) 1954-11-03 1955-11-02 X-ray tube voltage control circuit

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US (1) US2870340A (de)
BE (1) BE542484A (de)
CH (1) CH334122A (de)
DE (1) DE961199C (de)
ES (1) ES224744A1 (de)
FR (1) FR1144187A (de)
GB (1) GB796740A (de)
NL (1) NL103475C (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2931909A (en) * 1957-08-19 1960-04-05 Holger Andreasen Electric circuit for supplying an X-ray tube with a predetermined anode current which is equal to the substantially constant saturation current of the tube
US3163757A (en) * 1960-05-30 1964-12-29 Philips Corp X-ray tube control apparatus
US5123038A (en) * 1989-09-08 1992-06-16 U.S. Philips Corporation X-ray generator for operating an x-ray tube with parts of the tube connected to mass
US5497959A (en) * 1993-03-26 1996-03-12 Paper Converting Machine Company Coreless winding method and apparatus
US20040061021A1 (en) * 2002-09-27 2004-04-01 Butterworth Tad T. Rewinder apparatus and method
US20050087647A1 (en) * 2002-09-27 2005-04-28 Butterworth Tad T. Rewinder apparatus and method

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2931909A (en) * 1957-08-19 1960-04-05 Holger Andreasen Electric circuit for supplying an X-ray tube with a predetermined anode current which is equal to the substantially constant saturation current of the tube
US3163757A (en) * 1960-05-30 1964-12-29 Philips Corp X-ray tube control apparatus
US5123038A (en) * 1989-09-08 1992-06-16 U.S. Philips Corporation X-ray generator for operating an x-ray tube with parts of the tube connected to mass
US5497959A (en) * 1993-03-26 1996-03-12 Paper Converting Machine Company Coreless winding method and apparatus
US20040061021A1 (en) * 2002-09-27 2004-04-01 Butterworth Tad T. Rewinder apparatus and method
US6877689B2 (en) 2002-09-27 2005-04-12 C.G. Bretting Mfg. Co., Inc. Rewinder apparatus and method
US20050087647A1 (en) * 2002-09-27 2005-04-28 Butterworth Tad T. Rewinder apparatus and method
US7175127B2 (en) 2002-09-27 2007-02-13 C.G. Bretting Manufacturing Company, Inc. Rewinder apparatus and method

Also Published As

Publication number Publication date
GB796740A (en) 1958-06-18
ES224744A1 (es) 1955-12-16
NL103475C (nl) 1963-01-15
BE542484A (fr) 1956-04-30
FR1144187A (fr) 1957-10-10
CH334122A (de) 1958-11-15
DE961199C (de) 1957-04-04

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