US2730627A - X-ray stabilizer - Google Patents

Description

Jan. 10, 1956 J. E. JACOBS X-RAY STABILIZER Filed Jan. 11, 1952 k REGULATED OUTPUT INPUT UNREGULATED INVENTOR. JOHN E. JACOBS United S a e P t X-RAY STABILIZER John E. Jacobs, Milwaukee, Wis., assignor to General Electric Company, a corporation of New York Application January 11, 1952, Serial No. 266,052

18 Claims. (Cl. 250-'-97) The present invention relates in general to electronics, and has more particular reference to the provision of means for regulating the intensity of X-ray beams to produce beams of uniform intensity. The invention, while not necessarily so limited, is particularly useful for the regulation of X-ray beams resulting from the operation of X-ray generator tubes, especially where the generator tube is electrically energized by alternating current electrical power.

X-ray generator tubes commonly comprise an anode forming an electron target, and an electron emitting'cathode sealed with the anode in an evacuated envelope, the cathode being disposed in position to emit electrons for delivery at high speed upon the anode target, X-rays being generated at and emitted from said anode target in response to electron impingement thereon at high speed. While the cathode may comprise any suitable electron emitter, it commonly comprises a filamentary element adapted to be electrically energized, from a source outwardly of the envelope, for electron emission from the filament within the envelope; and in order to drive the so emitted electrons at high speed from the cathode and to cause the same to impinge upon the anode, electrical potential of high order is commonly applied, from a source outwardly of the envelope, between the anode and cathode.

X-ray generators, in common with other electron flow devices, have self-rectifying characteristics, that is to say, electron fiow takes place in one direction only from cathode to anode. As a consequence, where alternating current potential is applied between the anode and cathode, electron flow and resultant X-ray production occurs only during alternate half cycles of the electron driving potential applied between the anode and cathode of the generator, the generator being inactive during the intervening half cycles of electron driving energy.

X-ray generators may be, and occasionally are, operated by the application ofuni-dire'ctional electron driving potential between the anode and cathode. In such cases, the generator operates continuously for the production of X-rays, through the continuous delivery of electrons from the cathode upon the anode target under the influence of uni-directional anode-cathode electron driving potential.

X-ray generators also are frequently operated by first rectifying alternating current energy to obtain uni-directional potential for application between the anode and cathode of the generator. In such cases, where full wave rectification is employed, the generator may function continuously for the production of X-rays. Where half wave rectification is employed, however, the generator operates for the production of X-rays only during alternate half cycles of generator energizing power, being inactive duringintervening power half cycles.

For many purposes it is highly desirable, if not essential, to obtain X-rays of uniform intensity,- whether the rays be produced continuously or during alternate half cycles of energizing power, lack of uniformity of ray intensity being usually due to power fluctuations in the power source or in the power supply line from which electron driving potential, applied between the anode and cathode of the generator, is derived. Commercially available voltage regulators usually function satisfactorily only in systems supplying an electrical load which draws energy in equal quantities during the successive cycles of alternating current power supply. As a consequence, such commercially available regulators are not able to provide satisfactory regulation in alternating current power supply systems where energy is drawn by the load during alternate half cycle periods, as is the case where the load is an X-ray generator operating as a self-rectified device, oi when supplied with alternating power which has been subjected to half wave rectification.

An important object of the present invention is to proe vide relatively simple and inexpensive, yet highly eflicient means for regulating the operation of X-ray generators in order to obtain an X-ray output of substantially uniform intensity from the generator during the operation thereof, such means being particularly well suited for regulating generators when operated as self-rectifying devices, or when energized by alternating current power which has been subjected to half wave rectification, such means being also adapted for use as a highly efiicient regulator for generators energized from a uni-directional power source, especially when such source comprises a full wave rectitying system. v

Another important object is to provide regulating means of the character mentioned and operable, in response to variations in the intensity of an X-ray beam produced by the generator under regulation, to appropriately increase or decrease the electrical power applied to the generator for the operation thereof as such.

Another important object is to employ a detector element comprising a semi-conductor sensitive to X-rays, for the purpose of controlling the regulator means of the present invention, and to dispose said detector element in the X-ray beam of the generator to be regulated; a further object being to employ a semi-conductor having amplification characteristics as an X-ray sensitive detector for regulating energizing power delivered to an X-ray generator for the operation of the same; a still further object being to employ cadmium or mercury sulphide, or cadmium s'elenide as an X-ray sensitive semi-conductor material.

Another important object is to provide a regulator of the character mentioned comprising a balanced electrical bridge, one leg of which embodies an X-ray sensitive detector element adapted to be exposed in an X-ray beam produced by an X-ray generator to measure or detect changes in beam intensity and thereby correspondingly unbalance the bridge, the regulating system including means controlled by another leg of the bridge for increasing or decreasing the energizing power applied on the X- ray generator in accordance with the measured decrease or increase in measured X-ray intensity.

The foregoing and numerous other important objects, advantages, and inherent functions of the invention will become apparent as the same is more fully understood from the following description, which, taken in connection with the accompanying drawing, discloses a preferred eiiibodiment of the invention.

The accompanying drawing comprises a schematic wiring diagram illustrating an X-ray beam stabilizer e'inbodying the present invention.

Toillust rat'e the invention, the drawing shows a supply line comprising conductors 10 and 10' adapted for con-j nect ion with a suitable source of unregulated altern' current power, as at 11 and 11, said supply line 'bemg' adapted for connection, as at 12 and 12', with the anode and cathode of an X-ray generator to be regulated, preferably' through a step-up transformer. The connection of the line with the generator may, of course, be accomplished either for the operation of the generator as a self-rectified unit, or through a suitable rectifying systern, if desired. Such rectifying system may be arranged either for full wave or half wave rectification; and, of course, any suitable or desired auxiliary equipment, including metering and circuit controlling means, may be interconnected in the system between the generator and the supply line.

The regulating system of the present invention comprises means responsive to fluctuations in the intensity of an X-ray beam delivered by an X-ray generator energized through the power supply line 10, to increase or decrease the voltage between the connection points 12, 12', forming the delivery or output end of the line, in response to decrease or increase in the energy of the X-ray beam, and regardless of voltage fluctuations between the connection points 11, 11', which form the input end of the supply line. To this end, the regulating means comprises an electrical bridge 13 consisting of four legs extending between connection points 14, 15, 16 and 17. Between the connection points 14 and 15 the first leg of the bridge comprises a sensitive X-ray detector 18. Between the connection points 15 and 16 the second leg of the bridge comprises an adjustable resistor 19. Between the connection points 16 and 17 the third leg of the bridge comprises a resistor 20 and a condenser 21 interconnected in parallel relationship. Between the connection points '14 and 17 the fourth leg of the bridge comprises a resistor 22 and a condenser 23 interconnected in parallel relationship. The connection point 17 is preferably connected with a grounded conductor 24.

To provide uni-directional power for the operation of the system, a pair of electronic rectifiers 25, 25', may be employed, said rectifiers having filamentary cathodes 26, 26', and plates 27, 27'. For the operation of the rectifiers a transformer 28, having a primary winding 29, may be employed. The primary winding may be connected between the line conductors 10 and 10; and the transformer 28 may have a main secondary winding 30 and a pair of auxiliary secondary windings 31 and 31. The windings 31 and 31, respectively, may be connected with the filaments 26 and 26 of the rectifiers to energize the same for electron emission. The main secondary winding 30 of the transformer 28 may be provided with a center tap for connection with the ground conductor 24. The opposite ends of the main secondary transformer winding 30 may be connected, respectively, with the plates 27 of the rectifier element 25, and one of said plates 27 may be electrically connected with the cathode 26 of the rectifier element 25. The plates 27 of the rectifier element 25 may be electrically interconnected to gether and with a conductor 32, with which the bridge 13 is also electrically connected as at the connection point 16. The cathode 26' of the rectifier unit 25 may be electrically connected with a conductor 32, with which the electrical bridge 13 is also connected as at the connection point 14.

The system also includes an autotransformer winding 33 and a saturable core transformer 34, comprising inductive windings 35 interconnected in series and a saturating winding 36. The autotransformer winding 33 and the inductive windings 35 may be interconnected in series between the line conductors 10 and 10' at the input end of the line, the input side of the line 11 being connected with the autotransformer winding 33 intermediate the opposite ends thereof. The saturating winding 36 of the saturable core transformer may be interconnected between the conductor 32' and the interconnected anode plates 37 of a pair of electron flow devices 38. These devices 38 comprise electron flow valves having electron emitting cathodes 39 and electron flow control grids 40 in addition to the anodes 37, the cathodes 39 being electrically connected with the grounded conductor 24. The control grids 40 of the control devices 38 are electrically interconnected and are connected with the conductor 32' through a resistor 41 and a condenser 42, which are interconnected in parallel relationship between the grids 40 and the conductor 32.

Means is provided for controlling the operation of the devices 38 in accordance with electrical conditions prevailing in the bridge 13. To this end, the control grids 40 of the devices 38 may be electrically connected with the anode plate 43 of an electronic amplifier 44 having an electron emitting cathode 45 electrically connected with the conductor 32, preferably through an electronic device 46 comprising a gas filled tube representing a constant voltage drop of desired value. The cathode 45 is also electrically connected with the grounded conductor 24, as through resistors 47 and 48 interconnected in series between the conductor 24 and the cathode 45. The amplifier 44 may comprise control grids 49, and 51. The grid 49 may be connected directly with the cathode 45. The grid 50 may be connected with the cathode'through the resistor 47 and with the grounded conductor 24 through the resistor 48, and the grid 51 may be connected with the bridge 13, as at the connection point 15, through a resistor 52.

An electrical network, comprising condensers 53, 54 and and a resistor 56, may also be interconnected between the conductor 32 and the circuit including the resistor 52 between the grid 51 and the connection point 15. To this end, one side of each of the condensers 53, 54 and 55 may be electrically interconnected together and with one end of the resistor 56. The condensers 53 and 54 may be connected, respectively, with the opposite ends of the resistor 52; and the condenser 55 and the resistor 56 may be connected with the conductor 32.

The ray sensitive semi-conductor element 18 preferably comprises a photosensitive semi-conductor material of the sort described in co-pending applications for United States Letters Patent, Serial No. 190,801, now Patent No. 2,706,790, filed October 18, 1950; Serial No. 228,333, filed May 25, 1951; and Serial No. 232,073, now Patent No. 2,706,79l, filed June 18, 1951, the same comprising the crystalline sulphide salts of cadmium or mercury, or the selenide of cadmium, since these materials, as disclosed in the aforesaid applications for United States Letters Patent, have been found to be semi-conductors usefully sensitive to X-rays. For the purpose of the present disclosure, a semi-conductor may be defined as a substance having electrical resistance, or reactance, or both, which vary in accordance with the intensity of light or other rays to which the substance is exposed. Electrical resistance and electrical reactance, either inductive or capacity reactance, or both, are the characteristics of electrical conductors which tend to prevent or impede the fiow of electrical current therethrough under the in fiuence of an electromotive force, the combined fiow resistive effect in a given conductor material being commonly referred to as the electrical impedance of the material.

in the absence of rays to which it responds, a semiconductor may have impedance characteristics of such high order as to constitute it as a virtual insulator capable of substantially preventing flow of electrical current therethrough. The impedance of a semi-conductor, when irradiated with rays to which it responds, may be reduced as a proportional function of incident ray intensity, whereby the material becomes electrically conducting in proportion to the intensity of exciting rays impinging thereon.

A semi-conductor usually is usefully responsive only to rays of the particular character which affect it, being relatively unresponsive to other rays. Perhaps the most widely known semi-conductors are the so-called photosensitive materials which, in the absence of visible light, are virtual insulators, but which become electrically con ductive in the presence of light rays in the visible light spectrum and adjacent infrared and ultraviolet portions avarice? thereof. Such photosensitive materials in recent years have gone into widespread use in photoelectric control equipment, but are not usefully responsive to 'X-rays; nor, indeed, prior to the discoveries described in the aforesaid co-pending applications for United States Letters Patent, was it known how to apply the sulphides of cadmium and mercury and the selenide of cadmium precisely for X-ray detecting purposes. As pointed out in said co-pending applications for United States Letters Patent, exposure of crystals of cadmium or mercury sulphide or of cadmium selenide to X-rays in the manner taught in said co-pending applications, .in the total absence of visible light, causes the impedance of the crystal material to change substantially exactly in proportion to the intensity of impinging X-rays. Where the applied X-rays are of pulsating character, the impedance change in the crystal material follows the pulsations oi the impinging X-rays, and consequently will correspondingly affect a circuit in which the crystal material is electrically connected.

X-rays produced by operation of the usual 'X-ray generating tube electrically excited by alternating current power, as for instance at 60 cycles, comprise X-ray energy pulsations at a frequency corresponding with the frequency of the energizing power applied to the generator for the operation thereof. ,X-rays of uniform or nonpulsating character can, of course, be produced and applied upon the sensitive crystal material, in which case the impedance of the crystal material does not fluctuate, but remains constant at a value corresponding with the uniform intensity of the non-pulsating ray applied thereto. In either case the impedance of the irradiated material will correspond with the intensity .of the impinging ray.

The named X-ray sensitive semi-conductors also exhibit impedance characteristic changes when exposed to light rays within the visible light spectrum, the extent of such visible light induced impedance changes being proportional to the intensity of impinging light rays; and, as disclosed in the above mentioned co-pending applications for United States Letters Patent, when the semiconductor material is exposed to light rays and simultaneously to X-rays, the impedance of the material includes values which correspond with the intensity of visible light rays as well as of Xerays impinging thereon. It is therefore desirable, in applying the named semiconductors for X-ray detection purposes, either to exclude visible light rays from the detector material, was by enclosing the element 18 in a light-tight casing, which however is transparent to X-rays, or otherwise to assure that rays other than X-rays applied to the element 18 be of uniform intensity, in order not to variably afiect the impedance of the detector element other than in response to X-rays impinging thereon.

The named X-ray sensitive semi-conductors inthe presence ,of visible light show minimum impedance Values when exposed to light rays of particular wave length characteristic of the materials. In this connection, cadmium sulphide, for example, shows minimum impedance when bathed or biased with light having wave lengths of the .order of 5200 Angstroms. Accordingly, the effective maximum sensitivity of the named materials for X-ray detection purposes maybe accomplished by applying a visible -light .bias of uniform intensity to the detector material at a wave length producing the minimum light controlled impedance component in the material; and, accordingly, means may be provided for applying suchyisible light bias to the element 1.8, if desired.

The named X-ray sensitive materials comprise what may be termed electron donor substances. 1 When electrical potential is applied :across an element comprising one .of the named materials in the presence of X-rays applied thereto, currents ,in excess of 1.0 times the cur. rent resulting .from :primary ionization of the vcrystal in response to X-ray irradiation :are obtained. Any explanation of this phenomenon must account for the release of additional electrons in the crystal to produce the observed current multiplication. The energy necessary to produce this additional or amplified current in the crystal material can only be derived from the crystal itself. Accordingly, the crystals comprise excess electron or donor type semi-conductors which operate, in a sense, as current amplifiers under the control of visible, as well as invisible, light rays impinging thereon. In this connection, it is thought that electron donor centers in the crystal material are ionized by impingement thereon of primary electrons, equilibrium occurring when electrons are being trapped to form donor centers at the same rate at which such centers are ionized.

By disposing the element 18 in the path of an X-ray beam emitted by a generator to be regulated, either in the total absence of visible light, or in the presence of visible light of'uniform intensity, whether or not applied as a sensitizing light bias of selected wave length, the impedance value of the element 18 in the electrical bridge 13 will at all times correspond with the intensity of the X-ray beam to which it is exposed. The bridge 13 may be balanced by adjustment of the resistor 19 which, if desired, may be calibrated in terms of X-ray intensity to be maintained. In the absence .of incident X-rays the element 18 assumes an exceedingly high impedance value approximating an open circuit. For any given intensity of incident X-rays thereon, the element 18 behaves in effect as a resistor. The electrical bridge 13 being balanced by operation of the adjustable resistor 19 for a given intensity, any change in the intensity of the X-ray beam results in a change in the apparent resistance of the element 18, which consequently unbalances the bridge in one direction or the other, such unbalance being measured or indicated in terms of a change in potential between the bridge connection point 15 with respect to the conductor 32 or the conductor 32'. This change in relative potential of the bridge connection point 15 may be employed to correspondingly regulate the line voltage between the conductors 10 and 10, and thus alter the voltage applied to the controlled generator in a direction to maintain the intensity of the generator produced X-ray beam at the desired level.

To this end, as shown in the drawing, the operation of the amplifier 44 is controlled in response to the relative potential atthe connection point '15 to apply a corresponding amplified potential across the plate load resistor 41 of the amplifier 44, such voltage fluctuating in accordance with the changes in the relative potential of the connection point 15. The voltage or potential which thus appears across the resistor 41 ,is employed for the control of the electron flow devices 38. These devices, in turn, control current flow between the conductors 24 and 32 through the winding 36 of the saturable core transformer '54. 'By thus varying the impedance of the wind: ings 35 of said'transformer 34, the transformation ratio of theautotransformer means is varied, thereby accom plish'ing the desired voltage control function.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the-several parts without departing from the spirit or scope of the invention, or sacrificing any of its attendant advantages, the form herein disclosed being a preferred embodiment for the purpose of illustrating the invention.

The invention is hereby claimed as follows:

l. The method :of regulating an electrical power operated ray generator, which comprises the application of cyclically pulsating electrical energy upon the generator through a supply line having a transformer and an interconnected variable impedance component, applying generated 'rays'to ray responsive semi-conductor means, measuring variations of ray intensity in terms of ray induced 7 changes in the apparent impedance of the semi-conductor means, and regulating generator actuating energy by adjusting the variable impedance component in accordance with the so measured variations in the apparent impedance of the semi-conductor means.

2. The method of regulating an electrical power operated ray generator, which comprises the application of cyclically pulsating electrical energy upon the generator through a supply line having a transformer and a variable impedance component connected in shunt relationship across the supply line, applying generated rays to ray responsive semi-conductor means of the class including the sulphides of cadmium and mercury and the selenide of cadmium having amplifying characteristics when irradiated, measuring variations of ray intensity in terms of ray induced changes in the apparent impedance of the semiconductor means, and regulating generator actuating energy by adjusting the variable impedance component in accordance with the so measured variations in the apparent impedance of the semi-conductor means.

3. The method of regulating an electrical power operated X-ray generator, which comprises the application of cyclically pulsating electrical energy upon the generator through a supply line having a transformer and saturable core reactance means forming a variable impedance component connected in shunt relation across the supply line, applying generated X-rays to ray responsive semi-conductor means having amplifying characteristics, measuring variations of ray intensity in terms of ray induced changes in the apparent impedance of the semi-conductor means, and regulating generator actuating energy by varying the saturation of said reactance means in accordance with the so measured variations in the apparent impedance of the semi-conductor means.

4. Apparatus for regulating an electrical power operated ray generator, comprising power supply means including a supply line for energizing the generator, ray sensitive semi-conductor means adapted for disposition as a ray responsive detector in the path of rays emitted by the generator, electrical circuit means interconnected with said semi-conductor for measuring the ray induced response of said detector in terms of changes in the apparent impedance of said detector, said supply means including an energy transmitting transformer, connected in said supply line and interconnected variable impedance means for controlling the energy output of said line, and translation means for adjusting said variable impedance means as a function of the response of said detector.

5. Apparatus for regulating an electrical power operated ray generator, comprising power supply means including a supply line for energizing the generator, ray sensitive semi-conductor means adapted for disposition as a ray responsive detector in the path of rays emitted by the generator, means for measuring the ray induced response of said detector in terms of changes in the apparent im pedance of said semi-conductor, comprising an electrical bridge circuit in which said semi-conductor is electrically connected as a leg of said bridge, said supply means including an energy transmitting transformer, connected in said supply line and interconnected variable impedance means for controlling the energy output of said line, and translation means for adjusting said variable impedance means as a function of the response of said detector as measured in said bridge circuit.

6. Apparatus for regulating an electrical power operated ray generator, comprising power supply means including a supply line for energizing the generator, ray sensitive semi-conductor means adapted for disposition as a ray responsive detector in the path of rays emitted by the generator, means for measuring the ray induced response of said detector in terms of changes in the apparent impedance of said semi-conductor, comprising an electrical bridge circuit in which said semi-conductor is electrically connected as a leg of said bridge, said supply means including an energy transmitting transformer, connected in said supply line and interconnected variable impedance means connected across the supply line for controlling the energy output of said line, and translation means for adjusting said variable impedance means as a function of the response of said detector.

7. Apparatus for regulating an electrical power operated ray generator, comprising power supply means including a supply line for energizing the generator, ray sensitive semi-conductor means adapted for disposition as a ray responsive detector in the path of rays emitted by the generator, electrical circuit means interconnected with said semi-conductor means for measuring the ray induced response of said detector in terms of changes in the apparent impedance of the semi-conductor means, said supply means including an energy transmitting transformer and variable impedance means interconnected across said power supply line for regulating the delivery of operating power to the generator, and translation means operatively associated with said circuit means and with said variable impedance means for adjusting the same to regulate the delivery of operating power to the generator in accordance with changes in the apparent impedance of said semiconductor means as measured by said circuit means.

8. Apparatus for regulating an electrical power operated ray generator, comprising power supply means including a supply line for energizing the generator, ray sensitive semi-conductor means adapted for disposition as a ray responsive detector in the path of rays emitted by the generator, means for measuring the ray induced response of said detector in terms of changes in the apparent impedance of said semi-conductor means, comprising an electrical bridge circuit in which said semi-conductor means is electrically connected as a leg of said bridge, said supply means including an energy transmitting transformer and variable impedance means interconnected across said power supply line for regulating the delivery of operating power to the generator, and translation means operatively associated with said bridge circuit and with said variable impedance means for adjusting the same to egulate the delivery of operating power to the generator in accordance with changes in the apparent impedance of said semi-conductor means as measured by said bridge circuit.

9. Apparatus for regulating an electrical power operated ray generator, comprising power supply means including a supply line for energizing the generator, ray sensitive semi-conductor means adapted for disposition as a ray responsive detector in the path of rays emitted by the generator, electrical circuit means interconnected with said semi-conductor means for measuring the ray induced response of said detector in terms of changes in the apparent impedance of the semi-conductor means, said supply means including an energy transmitting transformer and a saturable core variable impedance component having a winding interconnected across said power supply line for regulating the delivery of operating power to the generator, said component having a saturating winding, controllable means for variably energizing said saturating winding, and means for regulating said controllable means in accordance with changes in the apparent impedance of said semi-conductor means as measured by said circuit means.

10. Apparatus for regulating an electrical power operated ray generator, comprising power supply means for energizing the generator, ray sensitive semi-conductor means adapted for disposition as a ray responsive detector in the path of rays emitted by the generator, means for measuring the ray induced response of said detector in terms of changes in the apparent impedance of said semi-conductor means, comprising an electrical bridge circuit in which said semi-conductor means is electrically connected as a leg of said bridge, said supply means including an energy transmitting transformer and a saturable core variable impedance component having a winding interconnected with said power supply means for regulating the delivery '9 of operating power to the generator, said component having a saturating winding, controllable means for variably energizing said saturating winding, and means for regulating said controllable means in accordance with changes in the apparent impedance of said semi-conductor means as measured by said bridge circuit.

11. Apparatus for regulating an electrical power operated ray generator, comprising power supply means including a supply line for energizing the generator, ray sensitive semi-conductor means adapted for disposition as a ray responsive detector in the path of rays emitted by the generator, electrical circuit means interconnected with said semi-conductor means for measuring the ray induced response of :said detector in terms of changes in the apparent impedance of the semi-conductor means, said supply means including an energy transmitting transformer and a saturable core variable impedance component having a winding interconnected across said power supply line for regulating the delivery of operating power to the generator, said component having a saturating winding, an electron valve for controlling the supply of energizing power to said saturating winding, and means for controlling the flow of energizing power through said electron valve in accordance with changes in the apparent impedance of said semi-conductor means as measured by said circuit means.

12. Apparatus for regulating an electrical power operated ray generator, comprising power supply means for energizing the generator, ray sensitive semi-conductor means adapted for disposition as a ray responsive detector in the path of rays emitted by the generator, means for measuring the ray induced response of said detector in terms of changes in the apparent impedance of said semiconductor means, comprising an electrical bridge circuit in which said semi-conductor means is electrically connected as a leg of said bridge, said supply means including an energy transmitting transformer and a saturable core variable impedance component having a winding interconnected with said power supply means for regulating the delivery of operating power to the generator, said component having a saturating winding, an electron valve for controlling the supply of energizing power to said saturating winding, and means for controlling the flow of energizing power through said electron valve in accordance with changes in the apparent impedance of said semi-conductor means as measured by said bridge circuit.

13. Apparatus for regulating an electrical power operated ray generator, comprising power supply means including a supply line for energizing the generator, ray sensitive semi-conductor means adapted for disposition as a ray responsive detector in the path of rays emitted by the generator, electrical circuit means interconnected with said semi-conductor means for measuring the ray induced response of said detector in terms of changes in the apparent impedance of the semi-conductor means, said supply means including an energy transmitting transformer and a saturable core variable impedance component having a winding interconnected across said power supply line for regulating the delivery of operating power to the generator, said component having a saturating winding, an electron valve for controlling the supply of energizing power to said saturating winding, and electronic amplifier means for controlling the flow of energizing power through said electron valve in accordance with changes in the apparent impedance of said semi-conductor means as measured by said circuit means.

14. Apparatus for regulating an electrical power operated ray generator having an anode and a cathode, comprising power supply means including a supply line for applying electrical power to said anode and cathode, ray sensitive semi-conductor means adapted for disposition as a ray responsive detector in the path of rays emitted by the generator, electrical circuit means interconnected with said semi-conductor means for measuring the ray induced response of said detector in terms of changes in the apparent impedance of the semi-conductor means, a saturable-core variable impedance component having a winding interconnected across said power supply line for regulating the potential at which operating power is applied between the anode and cathode of the generator, asaid component having a saturating winding, an electron valve for controlling the supply of energizing power to said saturating winding, and means for controlling the flow of energizing power through said electron valve in accordance with changes in the apparent impedance of said semiconductor means as measured by said circuit means.

15. Apparatus for regulating an electrical power operated ray generator having an anode and a cathode, comprising power supply means including a supply line for applying electrical power to said anode and cathode, ray sensitive semi-conductor means adapted for disposition as a ray responsive detector in the path of rays emitted by the generator, electrical circuit means interconnected with said semi-conductor means for measuring the ray induced response of said detector in terms of changes in the apparent impedance of the semi-conductor means, a transformer having a saturating winding and a variable impedance winding connected across said power supply line, an electron valve connected with said saturating winding for energizing the same, and electronic amplifier means for controlling said electron valve in accordance with changes in the apparent impedance of said semi-conductor means as measured by said circuit means.

16. Apparatus for regulating an electrical power operated ray generator having an anode and a cathode, comprising power supply means including a supply line for applying electrical power to said anode and cathode, ray sensitive semi-conductor means adapted for disposition as a ray responsive detector in the path of rays emitted by the generator, electrical circuit means interconnected with said semi-conductor means and forming a bridge for measuring the ray induced response of said detector in terms of changes in the apparent impedance of the semiconductor means, rectifier means powered from said supply line for energizing said bridge, a transformer connected in said supply line, reactance means having a saturating winding and a variable impedance winding connected across said power supply line, an electron valve for energizing said saturating winding with power supplied by said rectifier means, and means for controlling said electron valve in accordance with changes in the apparent impedance of said semi-conductor means, as measured by said circuit means.

17. Apparatus for regulating an electrical power operated ray generator having an anode and a cathode, comprising power supply means including a supply line for applying electrical power to said anode and cathode, ray sensitive semi-conductor means adapted for disposition as a ray responsive detector in the path of rays emitted by the generator, electrical circuit means interconnected with said semi-conductor means and forming a bridge for measuring the ray induced response of said detector in terms of changes in the apparent impedance of the semi-conductor means, rectifier means powered from said supply line for energizing said bridge, a transformer connected in said supply line, reactance means having a saturating winding and a variable impedance winding connected across said power supply line, an electron valve for energizing said saturating winding with power supplied by said rectifier means, electronic amplifier means for controlling said electron valve in accordance with changes in the apparent impedance of said semi-conductor means, as measured by said circuit means, and an electrically reactive network embodying resistance and condenser means interconnected between said circuit means and said amplifier means for modifying the operation of the amplifier means.

18. Apparatus for regulating an electrical power operated ray generator having an anode and a cathode, comprising power supply means including a supply line for applying electrical power to said anode and cathode, ray sensitive semi-conductor means adapted for disposition as a ray responsive detector in the path of rays emitted by the generator, electrical circuit means interconnected with said semi-conductor means and forming a bridge for measuring the ray induced response of said detector in terms of changes in the apparent impedance of the semi-conductor means, rectifier means powered from said supply line for energizing said bridge, a transformer connected in said supply line, reactance means having a saturating winding and a variable impedance winding connected across said power supply line, an electron valve for energizing said saturating winding, means forming a source of constant potential, and means for controlling said electron valve in accordance with changes in the apparent impedance of said semi-conductor means, as measured against said source of constant potential by said circuit means.

References Cited in the file of this patent UNITED STATES PATENTS l,229,740 Furstenau June 12, 1917 2,503,075 Smith Apr. 4, 1950 2,537,914 Roop Jan. 9, 1951 2,542,022 Friedman Feb. 20, 1951 2,582,850 Rose Jan. 15, 1952 OTHER REFERENCES The Ehoto-Conductivity of Incomplete Phosphors by R. Frerichs, Physical Review, October 1, 1947, pages 594-601.

An Economical Industrial X-Ray Detector by R. Fre- 15 richs et 211., G. E, Review, August 1951, pages 42-45.

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