US1252504A - X-ray apparatus. - Google Patents

Description

H. C. SNOOK & G. H. WHITE.

X-RAY APPARATUS.

APPLICATION FILED MAY'ZG. 1915.

1,252,504. Patented Jan. 8,1918.

UNITED STATES PATENT OFFICE.

HOMER C. SNOO K, OF CYNWYD, AND GEORGE H. WHITE, OF HAVERFORD, PENNSYL- VANIA.

X-RAY APPARATUS.

Specification of Letters yatent.

Patented Jan. 8, 1918.

Application filed May 26, 1915. Serial N 0. 30,509.

To all whom it may concern:

.Be it known that we, HOMER C. SNOOK and GEORGE H. VI-UTE, citizens of the United States, residingrat Cynwyd and Havertord, counties of Montgomery and Delaware, respectively, State of Pennsylvania, have invented new and useful Improvements in X-Ray Apparatus, of which the following is a specification.

Our invention relates to a system for supplying to an X-ray tube or other translating device high potential uni-directional energy derived from alternating current or unidirectional current impulses.

Our invention resides in such a system which is applicable for producing a unidirectional impulse of high intensity in the consumption circuit, as for X-ray fluoroscopic purposes, for each semi-cycle ot' the alternating current or for each wave or semi-cycle of one sign only; and also for delivering to the consumption circuit, particularly when including an X-ray tube, unidirectional impulses ot lesser intensity.

Our invention resides also in such a system where all of the waves or semi-cycles of alternating current of one sign are suppressed or where waves or semi-cycles of both signs are used, and a portion only of the waves or semi-cycles of one sign or both signs. is employed, and particularly when substantially the last halt of said waves or semi-cycles of one sign or both signs is used for producing the uni-directional impulses of great intensity in the consumption circuit. And our invention resides further in such means cooperating with a synchro nously rotating switch which cooperates in suppressing from the consumption circuit any current impulses of improper direction resulting from the use of such portion, generally the last half, of such waves or semicycles of one sign or of both signs.

Our invention resides in the system and apparatus hereinafter described and claimed.

For an illustration of one of the forms our invention may take reference is to be had in the accompanying drawing, in which:

Figure 1 is a diagrammatic view illustrating circuits and apparatus embodying our invention.

Figs. 2 and 2 are representations of an alternating current explanatory of our invention.

Fig. 3 is an end elevational view of a term of commutator or contactor.

Fig. 4: is a side elevational view of the same.

Referring to Fig. 1, 1 and 2 represent the conductors supplying direct current to a clirect current motor M coupled to an alternating current generator G. Or M may rep resent the direct current side of an inverted rotary converter whose alternating current side is represented by G. The device G may be a synchronous alternating current motor, in which case the direct current motor M is omitted, and the synchronous motor will drive the hereinafter described apparatus in synchronism with the alternating current.

In the conductor 1 is arranged a motor starting rheostat 3. The generator G or the alternating current side of an inverted rotary G delivers alternating current to the conductors 4t and 5 communicating with the reversing switch 6 from one of whose terminals extend the conductor 7 to one terminal of the primary P of a step-up transtormer whose secondary is S. The other terminal of the reversing switch 6 connects by conductor 8 with the adjustable resistance 9 connected to the switch 10 adapted to engage any of the contacts 11 to 15 inclusive. The contact 11 communicates through conductor 1G with a brush 1? of a commutator Or rotary contactor 18 whose other brush 19 communicates through conductor 20 with a tap in the primary P. The contacts 1?! to 15 inclusive communicate respectively with different taps in the primary P.

The commutator 18 is secured upon the shaft 21 of the motor generator, inverted rotary, or synchronous motor. The shaft 21, when the dynamo-electric machine has four poles, makes one complete revolution for two complete cycles of the alternating current.

The commutator 18 comprises the tour conducting arcs or segments 22, 23, 24; and 25, of which 22 and 23 are electrically connected by conductor 26 and insulated from segments 24 and 25 which are connected together by conductor 27.

As shown, the commutator 18 is connected in series in the alternating current circuit including a part of the primary P of the step-up transformer. The brushes 17 and 19 are disposed at substantially 90 degrees from each other circumferentially of the commutator 18, and the segments 22 to 25 inclusive are in the example illustrated of such length as to correspond with substantially one half of one wave or semi-cycle of alternating current, the commutator 18 being secured in such angular position upon the shaft 21 with respect to the brushes that the alternating current circuit through the commutator 18 is closed at approximately the maximum 28, Fig. 2, of an alternating electro-inotive-force wave and broken at substantially the zero point 29, the dotted portions of Fig. 2 indicating the parts 01 the electro-motive-force waves which are not used. Fig. 2 therefore indicates that all the semi-cycles or waves 01" one si n, those below the line, are not used, and that the last half of each oi the waves or semi-cycles of opposite sign only is used.

In Figs. 3 and. a form of commutator 18 is illustrated in greater detail. It is shown secured in fixed relation to the shaft :21 by a pin 30, Fig. 4. in addition to the contact segments mentioned, there are between neighboring segments the four pairs or" metallic segments 31 and 32 insulated from each other and from he segments to in elusive by the insulation 33, the segments 31 and serving to avoid wear caused by the brushes 17 and 19 which would otherwise occur if the entire space between neighboring contact segments were filled entirely by insulation, the insulation 33 between segments 31 and of each pair assisting further in preventing the jumping of arcs to a distance from the brushes.

T he brushes 1'? and 19 are relatively thin as measured circumferentially of the coinmutator, and are preferably of laminated copper or the like and supported by the brush holders 34-, here shown as of the Baylis type.

A coupling 35, 1, couples the she ft 36 of the rectifying switch E to the shaft 21 in any suitable angular re ion for maintaining any desired angular relation between the commutator 18 and the rotating parts of the switch E.

The switch E may be of any suitable construction or type and in the example illustrated is similar to that disclosed in Letters Patent of the United States No. 954,056 to H. C. Snook. The switch comprises the stationary arcs 3? to 40 inclusive, of which 37 and 38 are connected to the terminal 41 of the secondary S and of which 39 and -i-O are connected to the terminal of the secondary S. ()pposed to these arcs are the arcs 43 to 46 inclusive of which 43 and 46 are connected by conductor 47 with the anode of the Xray tube X, and of which 44 and 45 are connected by conductor 48 through ammeter 49 with the cathode or negative terminal of the tube X.

Cooperating with the arcs are the cross shaft 36, the cross connectors 50 and being disposed parallel with each other and at right angles to the cross connectors and 53.

F represents in edge view a fluoroscopic screen between which and the target Z of the tube X is disposed the object (1 which is to be examined.

'1 he operation is as follows:

With the switch 10 in the position illustrated in 1, alternating electro-motive- .torce is impressed by device G upon the primary circuit through commutator 18 including that part of the primary P having small number of turns or convolutions. H

As the commutator 18 and switch E are rotated in synchronism. with the alternating current in the primary circuit, the commutator 18 suppresses all of the waves or semi-cycles of one sign and closes the circuit through the primary P at or near the maximum 28 of the electro-motive-torce waves or semi-cycles of" opposite sign, whereby uni-directional current flows through the primary P until the Zero or substantially Zero point 29 is reached, when the commutator 18 again interrupts or breaks the primary circuit.

Since the primary circuit is closed at substantially the maximum of an clcctro-motive-force wave, there is a sudden rush of current through the primary 1?, which results in a peaked wave or impulse of high intensity in the secondary S, and during its existence the cross connectors 51 and are in cooperation with arcs 38, 44 and 40, 46, respectively, so that a current impulse of high intensity may be passed through the tube from are 46 to are 44, the terminal 42 of the second ry S during the existence of this peaked current impulse being positive, and the terminal 41 negative.

It would be expected that during the decrease in strength of the primary impulse from its maximum to zero there would be in the secondary circuit a succeeding impulse 01 opposite sign to that of the impulse of high intensity passed through the tube X. But by the time the current impulse of high intensity in the secondary has reached zero or substantially zero value, the cross connectors 51 and 53 will have rotated to a position beyond the arcs 38, 44, and 40, 46, to such position that the succeeding electro-motive-force wave in the secondary circuit will not soon enough attain a voltage high enough to cause current to leap the then lengthened air gap.

In the position illustrated in Fig. 1 the primary circuit has just been closed, as at point 28, Fig. 2, and the cross connectors 51 and 53 have traversed half of the distance at which they cooperate with the arcs 38, 44 and 40, 46. By the time the segments 24 .ray tube.

"and 25 are leaving brushes 19 and 17, that is, after rotation of substantially 45 mechanical or 90 electrical degrees,-the cross connectors 51 and 53 will have rotated through a like number of degrees, and the angular extent of the arcs may be such that for such new position of the cross connectors there will be a substantial air gap between those cross connectors and the arcs, and so offering too great a resistance to the second electro-motive-force wave in the secondary circuit to allow passage of current thereover, which current, if allowed to pass, would be in the wrong direction for the X- ray tube.

However, the angular extent of the arcs of the switch E is substantially that described in said prior Patent 951,056 for purposes of rectification to direct energy from semi-cycles of both signs through the X- And when of such extent the switch E will operate as above described in connection with the commutator 18.

Only cross connectors 51 and 53 are utilized when commutator 18 is operative, to suppress all semi-cycles of one sign, the cross connectors 50 and 52 being idle.

WVhen it is desired to use energy from the waves or semi-cycles of both signs, the segments 22, 28, 24 and 25 of commutator 18 may all be electrically connected as by electrically connecting the conductors 26 and 27. Then, as represented in Fig. 2 the pri mary circuit will be closed during substantially the last half of the waves or semicycles of both signs, circuit closure for the wave of one sign being indicated between the points 28 and 29, as in Fig. 2, and for the waves of opposite sign between points 55 and 56. When so using energy from the waves or semi-cycles of both signs all the cross connectors 50 to 53 inclusive, of switch E, are utilized, cross connectors 50 and 52 now coming into use in addition to the crossconnectors 51 and 53 for the purposes above given.

It will be noted that when the commutator 18 is in circuit as indicated in Fig. 1, the number of turns in the primary P utilized is less than for any of the other positions of the switch 10. The use of such relatively smaller number of turns of the primary P results in the delivery by the secondary S of higher potential.

hen the switch 10 is moved into engagement with any of the contacts 12 to 15 inclusive, a greater number of turns of the primary P are utilized, and in such case the commutator 18 is out of circuit and there is passed through the primary P an alternating current, all the positive and negative waves or semi-cycles being utilized. In such case the switch E delivers uni-directional current to the tube X, as described in the prior Patent 951,056.

In place of the shaft 21 being that of the motor generator of the inverted rotary converter, it may be the shaft of a synchronous motor driven by a source of alternating current, the motor serving to rotate the shafts 21 and 36, and the alternating current from the source being directly led to the conductors 7 and 8.

If the commutator 18 should be so disposed that the primary circuit is closed at or substantially zero of an electro-motiveforce wave and accordingly broken at or near the maximum of such wave, there will be serious sparking at the commutator 18 because of the rupture of the current at the peak of the wave. By our preferred arrangement however, as illustrated, the cir cuit is closed at or near the maximum of the wave, and the closure of a circuit is accomplished with little or no sparking, and the circuit is then broken at substantially the zero value, where again the sparking is negligible.

For fluoroscopic purposes high intensity impulses of short duration may be employed. High voltage impressed upon the X-ray tube produces rays of great penetrating power. And due to the persistence of vision the current impulses through the tube need not succeed each other closely. However, when the source of alternating current is one of 60 cycles per second, by the apparatus hereinbefore described when commutator 18 is in circuit, the tube X will receive 60 impulse per second. If considerably fewer impulses per second are impressed upon the tube X they will occur at so great intervals that the persistence of vision will not suffice to maintain the effects upon the eye, and there will be observed a flickering effect.

hat we claim is:

1. The combination with a source of alternating current, of a commutator driven in synchronism with the alternating current, said commutator comprising a pair of segments electrically connected to each other, insulation between said segments, a pair of brushes with respect to which said segments and insulation rotate, a transformer, an X-ray tube in the secondary circuit of said transformer, a connection from one of said brushes to a point in the primary winding of said transformer and the other of said brushes connected to a switch, and connections from said transformer primary and said switch to said source of current.

2. The combination with a source of alternating current, of a commutator driven in synchronism with the alternating current, a transformer, an X-ray tube connected in the secondary circuit of said transformer, a pair of brushes bearing on said commutator and connected respectively with the primary of said transformer and with a switch, and connections from said transformer primary and said switch to said source of current.

3. The combination with a source of alternating current, of a commutator and a rectifying switch driven in synchronism with said current, a transformer, a translating device, said commutator and a switch intervening between the primary of said transformer and said source, said switch in one position connecting said commutator in series with a portion of the transformer primary, and in another position cutting out said commutator and cutting in a different number of turns of said primary.

4. The combination with a source of alternating current, of a commutator and a rectifying switch driven in synchronism with said current, a transformer, an X-ray tube, said commutator and a switch intervening between the primary of said transformer and said source, said switch in one position connecting said commutator in series with a portion of the transformer primary, and in another position cutting out said commutator and cutting in a greater number of turns of said primary.

5. The combination with a source of alternating current, of a commutator and a rectifying switch driven in synchronism with said current, a transformer, a translating device, said commutator and a switch intervening between the primary of said transformer and said source, said switch in one position connecting said commutator in series with a portion of the transformer primary, and in another position cutting out said commutator and cutting in a different number of turns of said primary, and an ad justable current restraining means in series with said switch.

6. The combination with a source of alternating current, of a commutator and a rectifying switch driven in synchronism with said current, a transformer, a translating device, said commutator and a switch intervening between the primary of said transformer and said source, said switch in one position connecting said commutator in series with a portion of the transformer primary, and in another position cutting out said commutator and cutting in a different number of turns of said primary, an adjustable current restraining means in series with said switch, and a reversing switch in the primary circuit.

7. The combination with a source of a1- ternating current, of a commutator driven in synchronism with the alternating current, a transformer, an X-ray tube connected in the secondary circuit of said transformer, and aswitch in one position connected in series with said commutator and the primary of said transformer and in another position connecting said transformer primary to said source of current independently of said commutator.

8. The combination with a source of alternating current, of a commutator driven in synchronism with the alternating current, a transformer, an X-ray tube connected in the secondary circuit of said transformer, a switch, said commutator and said switch intervening between the primary of said transformer and said source of current, said switch in one position connecting said commutator in series with a portion of the transformer primary, and in another position cutting out said commutator and cutting in a different number of turns in said primary.

9. The combination with a source of alternating current, of a commutator driven in synchronism with the alternating current, a transformer, an X-ray tube connected in the secondary circuit of said transformer, a switch, said commutator and said switch intervening between the primary of said transformer and said source of current, said switch in one position connecting said commutator in series with a portion of the transformer primary, and in another position cutting out said commutator and cutting in a greater number of turns of said primary.

In testimony whereof we have hereunto aflixed our signatures this 25th day of May, 1915.

HOh IER C. SNOOK. GEORGE H. WHITE.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. G.

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