US3409775A - Plural x-ray tube power supply having means for energizing the tubes for single or double operation - Google Patents

Description

Nov. 5, 1968 H. MAHLER ET PLURAL X-RAY TUBE POWER SUPPLY HAVING MEANS FOR ENERGIZING THE TUBES FOR SINGLE OR DOUBLE OPERATION Filed May 18, 1965 INVENT RS:

ATTO KNESS United States Patent PLURAL X-RAY TUBE POWER SUPPLY HAVING MEANS FOR ENERGIZING THE TUBES FOR SINGLE OR DOUBLE OPERATION Herbert Mahler and Johannes Seidel, Erlangen, Germany,

assignors to Siemens-Reiniger Werke Aktiengesellschaft,

Erlangen, Germany, a corporation of Germany Filed May 18, 1965, Ser. No. 456,611 Claims priority, application Germany, May 29, 1964, S 91,283 5 Claims. (Cl. 25094) ABSTRACT OF THE DISCLOSURE An apparatus for X-ray diagnosis is provided with means which make it possible to operate it with one X-ray tube or with a pair of X-ray tubes which can be set to operate jointly or alternately. These means include two transformers the secondary windings of which are connected with dry rectifier groups. The primary windings of the transformers are connected with regulating transformers which are connected to a three phase current net through a switch-over device and a timing switch. A manually operable selective switch can be set to various positions in which different relay switches are operated to provide selectively parallel operation of two X-ray tubes, eventually with separate high voltage regulation, alternate operation of the two X-ray tubes and operation of one X-ray tube.

This invention relates to an apparatus for X-ray diagnosis and refers more particularly to an apparatus for X-ray diagnosis which can operate with a single X-ray tube and which can be switched to a parallel operation or alternate operation with two X-ray tubes.

Various methods of X-ray diagnosis, in addition to the usual manner of operation with one X-ray tube in a single plane, require the simultaneous production of two X-ray pictures of a single object being photographed, usually in two planes which are perpendicular to each other. To carry .out these requirements it is known in prior art to connect two X-ray tubes in parallel to a single high voltage generator. An X-ray diagnosis apparatus of this type has above all the drawback that different dose outputs of the two X-ray tubes, which are made necessary by the different thicknesses of the object in the two associated photographic planes in order to produce films of the same blackness, can be set only by a corresponding selection of the current strength in the two X-ray tubes. However, the change in the dose output which can be attained by the change in the current of the X-ray tubes is too small in most cases to balance the differences in absorption in the two object planes, which are often considerable. Therefore, it is preferable to produce the required differences in the dose outputs delivered by the two X-ray tubes by changing the voltages of the X-ray tubes, since changes in voltages of X-ray tubes result in substantially higher changes in dose outputs than, percentagewise, equal changes in currents of Xray tubes.

British Patent No. 808,157 describes an apparatus for X-ray diagnosis operating with two X-ray tubes and having two separate high voltage generators for the X-ray tubes. The drawbacks of an apparatus of this type reside primarily in its high technical costs and the necessity for a large amount of space. Furthermore, since operation with one X-ray tube occurs much moreoften, one of the two high voltage generators remain unused.

British Patent No. 929,296 describes the use of simpler means, namely, it describes an apparatus for X-ray diagnosis operating with two X-ray tubes, wherein the 3,409,775 Patented Nov. 5, 1968 two X-ray tubes are connected to a single high voltage generator and wherein the circuit of one of the two X-ray tubes includes adjustable high voltage vacuum tubes, the regulatable drop in voltage of which can be utilized for the voltage adjustment of one of the two X-ray tubes. Even if one leaves out of consideration the high technical and operational costs required by the use of adjustable high voltage vacuum valve tubes, an apparatus of this type has, in the first place, the drawback that these expensive structural elements are required only when operating with two X-ray tubes, but are not required for operations with one X-ray tube which take place much more often. A further drawback consists in that the adjustable high voltage vacuum tubes can be used only to lower the high voltage in the X-ray tube connected in series with the high voltage vacuum tubes in relation to the voltage set for the other X-ray tube. This makes it necessary either to bring the object being photographed into a very precise position in relation to the two X-ray tubes, which is sometimes impossible for medical reasons, or to make the two X-ray tubes replaceable relatively to each other by means of a special device, or to provide relatively expensive additional high voltage switching means for the electrical switching over of the two X-ray tubes.

An object of the present invention is to eliminate the drawbacks of prior art constructions through the provision of an apparatus for X-ray diagnosis wherein all the constructional elements required for operation with two X-ray tubes, can be also utilized for operations with one X-ray tube which occur much more often, thereby attaining for the entire construction the greatest possible technical and operational efficiency.

Another object is to attain the greatest possible saving in space in an apparatus of the described type by arranging all the high voltage structural elements required for operation with one X-ray tube and for operation with two X-ray tubes, namely, the two high voltage generators and the high voltage switch, in a single oil-filled casing.

A further object consists in attaining the highest possible electrical output when operating with one X-ray tube by connecting the two generators in parallel, so as to be able to obtain the X-ray pictures in the shortest possible time.

Yet another object is the provision of means making it possible to switch, if desired, the two high voltage generators in series during operation with one X-ray tube, so as to make available the highest possible voltage for the photographing of hard rays.

A still further object is the provision of means making it possible to either set separately the voltage in the two X-ray tubes during operation with two X-ray tubes, the setting taking place by means of a setting button by connecting the two high voltage generators to .separate regulating transformers, so as to attain a constant blackening of the film in the case of objects which absorb quite differently in the two ray-receiving planes; or to set it jointly by a single setting button in that the low voltage connections of the two generators are interconnected in parallel and are connected with a single regulating transformer, so as to provide simple handling in the case of objects which do not have any substantial absorption differences in the two directions of illumination.

Still another object is to provide means for an'alternating operation 'with two X-ray tubes, wherein the two X-ray tubes are switched in alternately after each second picture taking. By way of example, an operation of this type is suitable for stereo-photographing.

A yet further object is to provide symmetrical grounding of the high voltage circuit in the voltage middle point for each of the above-described operational types.

Other objects of the present invention will become apparent in the course of the following specification.

In the accomplishment of the objectives of the present invention it was found advisable to provide an apparatus with two high voltage generators of the same construction and the same electrical dimensions which along with electrically actuated high voltage switching means are all located in a single oil-filled container. Each high voltage generator is composed of a high voltage transformer with a high voltage rectifier group. The secondary winding of each transformer is divided into an even number of divisional windings with equal outlet voltages and each divisional winding is connected with a dry rectifier group in full switch connection. The sides of the dry rectifier groups with the same voltage are interconnected in series. The low voltage contacts of the high voltage generators are c onnected with electrically operated low voltage switching means which are located outside of the common container. A switching device is connected with exciting coils of the high and low voltage switching means. The switching device can be switched into any one of five positions. In the first position the high voltage contacts of the two generators which are interconnected in parallel, are connected with a single X-ray tube. In the first and second positions the low voltage contacts of the two generators, which are interconnected in parallel, are connected with a single regulating transformer. However, in the second position the high voltage contacts of the two generators are connected with separate X-ray tubes. In the third position'the low voltage contacts of each generator are connected with a separate regulating transformer. In the third and fourth positions the high voltage contacts of the two generators are connected with separate X-ray tubes. However, in the fourth position the low voltage contacts are interconnected in parallel and are connected with a single regulating transformer. In its fifth position the switching device operates a switch which during a two X-ray tube operation connects the primary contacts of the high voltage generators with separate contacts of an alternating switch which is operated by the device releasing the picture taking in such manner that it places the two generators alternately and separately in operation from one picture taking to the next one. Throughout all types of operation each high voltage circuit is grounded in its symmetrical equal voltage central point.

The apparatus for X-ray diagnosis constructed in accordance with the principles of the present invention can be used in a more universal manner than all prior art X-ray apparatuses with comparable output. It was found from actual experience that the X-ray apparatus of the present invention requires only an insignificantly higher technical output than an X-ray apparatus of the same power suitable for only single X-ray tube operation. This is caused essentially by the fact that the total existing number of dry rectifier elements is the same in both cases for an apparatus for X-ray diagnosis with a single high voltage transformer, due to the same operational data and the easy possibility of dividing the rectifier tablets between two transformers. Furthermore, the present invention utilizes the consideration that the full output of the X-ray generator can be utilized only when operating with a single X-ray tube. During operation with two X-ray tubes, a high voltage generator set for operation with one X-ray tube can never be utilized completely due to the large number of photographs per unit of time which is always required in this type of operation (angiographic operation) and the resulting output limitations for the X-ray tube per each picture taking. The present invention provides, therefore, the possibility to considerably reduce the additional expenditure of high voltage structural elements for a simultaneous two X-ray tube operation which up to now has always been considerable and which provided a substantial impediment for the further utilization of this practice.

The invention will appear more clearly from the following detailed description when taken in connection with the accompanying drawing, showing by way of example, a preferred embodiment of the inventive idea.

The sole figure of the drawing is a diagram illustrating the electrical connections of the apparatus of the present invention in the inoperative position of the selective switch.

For the sake of clarity of illustration the drawing does not show the known regulating and overload protecting means for the setting of X-ray voltage, X-ray current and picture taking time, as well as the X-ray tube heating circuits.

The apparatus shown in the drawing has two high voltage transformers 1 and 2 which are secondarily symmetrically constructed and the secondary windings of which are each divided into two partial windings 3, 3' and 4, 4', respectively, with equal outgoing voltages. Each transformer is connected with a separate dry rectifier group 5, 5 and 6, 6 respectively. They are all, along with the high voltage switches which will be described in greater detail hereinafter, located in a common container 7 which is filled with oil. The primary winding 8 of the transformer 1 is directly connected with the regulating transformer 9, while the primary winding 10 of the transformer 2 can be selectively connected through a relay switch C either with the regulating transformer 9 or with another regulating transformer 11. The two regulating transformers are connected with the three-phase current net RST through a relay switch-over device A which is bridged by the relay switch B, and a timing switch 12. The contacts of the timing switch 12 are closed at the beginning of the X-ray photographing, so that a connection is provided between one of the regulating transformers 9, 11 or both of these transformers with the three-phase current net RST. After the set photographing time period has expired, the contacts of the timing switch 12 open so that the connection between the apparatus and the three-phase current net is interrupted, thereby terminating the photographing. The means for setting the photographing time period and for terminating the photographing are well known in the art and are not illustrated.

The relay switches A, B and C located in the low voltage circuit, as well as the relay switches D, E and F located in the high voltage circuit, are all connected to an operating device 13 which operates the switches depending upon the manually set location of a lever 14 which can be placed in positions designated as I, II, III, IV and V.

The operation is as follows:

In the position I of the selective switch 14 the relay switches B, C and F are attracted. Consequently the primary windings of the two high voltage transformers are connected with the regulating transformer 9, and the two X-ray tubes 15, 16 are separately connected with the high voltage contacts of the two high voltage generators. Therefore, in this position of the selective switch a parallel operation with two X-ray tubes with a common high voltage regulation is possible.

In the position II of the selector switch 14 the relay switches B and F are attracted. This switching position differs from the switching position I in that the switch relay C has dropped and thus the primary winding 10 is connected with the regulator transformer 11. Thus in this switching position a parallel two X-ray tube operation is possible with separate high voltage regulation for the two tubes.

In position III the relay switches B, C and E are attracted. Then the two X-ray tubes 15, 16 are inoperative, while the Xray tube 17 is connected with the high voltage contacts of the two generators which are secondarily connected in parallel. This switching position permits operation with one tube while utilizing the output of both generators.

In position IV the relay switches B, C and D are attracted. Then the X-ray tube 17 is connected with the high voltage contacts of the two generators which are connected in series. This position permits, therefore, operation with extreme hard rays with a double value of the high voltage set at the regulating transformer 9.

In position V of the selector switch 14 only the relay switch F is attracted. Then the two X-ray tubes 15, 16 are separately connected with the outlets of the two high voltage generators. Furthermore, the primary windings 8 and are separately connected to the regulating transformers 9 and 11. In this position of the selector switch the relay switch A must be alternately attracted and drop off during each picture taking by means not shown in the drawing. Consequently during each first picture taking the generator 1 is connected with the current supplying three-phase net through the regulating transformer 9, while during the following picture taking the generator 2 is connected with three-phase net through the regulating transformer 11. Therefore this position of the selector switch makes possible an X-ray stereo operation.

It is apparent that the example described above has been given solely by way of illustration and not by way of limitation and that it is subject to many variations and modifications within the scope 'of the present invention. All such variations and modifications are to be included within the scope of the present invention.

What is claimed is:

1. In combination with a source of electrical energy, a pair of X-ray tubes and a third X-ray tube, an apparatus for X-ray diagnosis with single and double X-ray operation, said apparatus comprising two high voltage generators of the same construction and the same electrical dimensions, each of said generators having a high voltage transformer and a high voltage dry rectifier group having direct voltage contacts, each of said transformers having a primary winding and a secondary winding, each of said secondary windings having an even number of divisional |windings with equal outlet voltages, means connecting each divisional winding with a separate rectifier group, high voltage switches connected with said rectifier groups, a single container adapted to be filled with oil and containing said generators and said high voltage switches, two regulating transformers having secondary windings with contacts, an operating device movable manually into a plurality of positions, operating switches connected with said operating device for selectively connecting different direct voltage contacts of the dry rectifier groups with different X-ray tubes, other operating switches connected with said operating device for simultaneously grounding the direct voltage center of each X-ray tube connection, and other operating switches connected with said operating device for connecting the primary windings of the high voltage transformers with the secondary winding contacts of the regulating transformers, depending upon the selected connection of the direct voltage contacts of the dry rectifier groups with the X-ray tubes and a timing switch connecting said regulating transformers with said source.

2. An apparatus in accordance with claim 1 wherein said operating device has two positions, and wherein in one of said positions some of said operating switches connect the direct voltage contacts of the dry rectifier groups in parallel and with the third X-ray tube and connect the primary windings of said high voltage transformers in parallel and with one of said regulating transformers, and wherein in the other one of said positions some of said operating switches connect each primary winding of a high voltage transformer with a separate regulating transformer and connect the direct voltage contacts of each dry rectifier group with a separate X-ray tube of said pair of X-ray tubes.

3. An apparatus in accordance with claim 1, wherein said operating device has three positions, and wherein in one of said positions some of said operating switches connect the direct voltage contacts of the dry rectifier groups in parallel and wherein in the second one of said positions some of said operating switches connect the direct voltage contacts of the dry rectifier groups in series, and wherein in both the first and the second positions said operating switches connect the direct voltage contacts of the dry rectifier groups with the third X-ray tube and also connect the primary windings of said high voltage transformers in parallel and with one said regulating transformers, and wherein in the third position some of said operating switches connect each primary winding of a high voltage transformer with a separate regulating transformer and connect the direct voltage contacts of each dry rectifier group with a separate X-ray tube of said pair of X-ray tubes.

4. An apparatus in accordance with claim 1, wherein said operating device has four positions and wherein in one of said positions some of said operating switches connect the direct voltage contacts of the dry rectifier groups in parallel and wherein in the second one of said positions some of said operating switches connect the direct voltage contacts of the dry rectifier groups in series, and wherein in both the first and the second positions said operating switches connect the direct voltage contacts of the dry rectifier groups with the third X-ray tube and also connect the primary windings of said high voltage transformers in parallel and with one of said regulating transformers, and wherein in the third position some of said operating switches connect each primary winding of a high voltage transformer with a separate regulating transformer and wherein in the fourth position some of said operating switches connect the primary windings of said high voltage transformers in parallel and with one of said regulating transformers, and wherein in the third and fourth positions some of said operating switches connect the direct voltage contacts of each dry rectifier group with a separate X-ray tube of said pair of X-ray tubes.

5. An apparatus in accordance with claim 1, wherein said operating device has an additional position, said apparatus comprising a switch over device having switch over contacts, and switching means connected with said operating device and operable in said additional position when said pair of X-ray tubes is energized to connect the primary winding of each of said high voltage transformers with a separate switch over contact of the switch over device for alternately connecting the primary windings during a sequence of X-ray operations.

No references cited.

RALPH G. NILSON, Primary Examiner.

A. L. BIRCH, Assistant Examiner.

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