US1954612A - X-ray installation - Google Patents

Description

April 10, 1934. A, BQUWERS 1,954,612

x-RAY INSTALLATION Filed Aug. 8. 1929 2-Sheets-Sheet 1 /a N f j g r o a f-f- 1 lucen/7501": eilerowwercm April 170, 1934. A. BOUWERS I 1,954,612

x-'RAY INSTALLATION Filed Aug. 8. 1929 2 Sheets-Sheet 2 Patented Apr. 10, 1934 UNITED STATES PATENT OFFICE X-RAY INSTALLATION Eindhoven,

Netherlands, a limited-liability company of the Netherlands Application August 8,

1929, Serial No. 384,400

In the Netherlands March 26, 1927 3 Claims.

An object of the present invention is to pro-` rI vide an arrangement adapted for carrying this principle into effect, which is Very simple and practical.

Another object is to provide means with the aid of which, a short exposure may be taken at any desired moment.

For carrying out the objects of the invention I have provided in an X-ray installation with an X-ray tube having an auxiliary electrode between the cathode and the anticathode, means for alternatively impressing on the auxiliary electrode a low potential that prevents the passage of current across the tube and a higher potential allowing the discharge of a condenser connected in parallel with the tube. As this auxiliary electrode .30. use may be made of the usual device for directing the cathode rays on a limited portion of the anticathode, the so called focussing device.

Other objects and features will be apparent from the following description considered in connection with the accompanying drawings, in which Figure 1 represents one embodiment of the invention and Figure 2 a modication employing a battery as the source of electrical energy.

In the drawings the primary side of a transformer is indicated by 1 and is connected to a suitable source of alternating current via the regulating resistance 3. The secondary winding 2 of thel transformer is connected to the anode of a rectifying valve 4 the cathode of which is connected to one of the plates of a condenser 5, the other plate being grounded. During the half cycles in which the anode of the valve 4 has a positive potential a current may flow unidirectionally to the condenser 5. Discharge of the latter is not possible except through the X-ray tube 6 which is connected across the condenser 5. The tube represented in the figure has an incandescent cathode 8 and an anticathode 7 of the usual type. Preferably, however, the anti- (Cl. Z50- 34) cathode is constructed so as to be movable according to prior application Ser. No. 186,522 of April 25, 1929. The outer wall of the tube comprises a metal portion 9 connected by fusion to glass parts by which it is insulated from both electrodes of the tube. The incandescent cathode 8 is surrounded by an auxiliary electrode 10. The latter constitutes the focussing device that directs the beam of cathode rays on a small area of the anticathodes target. The auxiliary electrode lo and the grounded cathode 8 are connected to two contacts of a commutator 11.

In the position shown in the drawings the commutator gives ground potential to the device 10, whereby the tube is rendered non-conductive, the electrons emitted by the cathode being retained by the space charge between the device 10 and the incandescent filament.

Meanwhile the condenser 5 .is gradually charged `up by the transformer in collaboration with the rectifier 4. At the moment at which the short exposure should be made, the commutator 11 is turned to its opposite position connecting thereby the device 10 to a point of the transformer winding 2 that has a potential lying between that of the anticathode and that of the cathode. The device 10 then during a very short time gets a positive potential relative to the cathode and the electrostatic eld between these members is directed so as to impart an acceleration to the electrons. The condenser now discharges via the X-ray tube.

It is also possible to use a battery for impressing the desired potentials on the device 10 instead of connecting the latter to the transformer winding. An arrangement according to this modication is illustrated in Fig. 2, the arrangement being such 'that in the position of commutator 11 shown in the drawings the positive pole of a battery 12 is in connection with the cathode and the negative pole is in connection with device 10, the tube then being inoperative. In the other position, indicated in dotted lines, the connections with the battery are interchanged and the electrostatic eld between device 10 and cathode 8 is so as to permit the electrons to flow in the direction to the anticathode. In this arrangement the duration of the exposure depends on the time of the commutator being in operative position or on the capacity of the condenser together with the temperature of the filament. The passage of cur- It is obvious that, provided the condenser is in a charged condition, the operator is substantially free in choosing the moment at which the discharge shall take place.

No X-ray energy is emanated as long as the commutator remains in its operative position whereas the current in no time reaches its maximum Value when the commutator is turned over.

To some extent the focussing device plays con-I sequently the part fullled by the control grid in discharge tubes utilized in Wireless telephony and telegraphy.

What I claim is:

1. An X-ray installation for making short X-ray exposures, comprising a transformer, a storage condenser, and a rectier connected in series with the secondary of said transformer, said transformer substantially fully charging said condenser only over a plurality of cycles, an X-ray tube connectedl across said condenser and comprising a cathode, an anticathode and an auxiliary electrode, and means for impressing on the auxiliary electrode a low potential for preventing the passage of current across said tube, and a higher potential for causing the discharge of the condenser.

2. An X-ray installation for making short X- ray exposures, comprising a transformer, a storage condenser, and a rectifier connected in series with the secondary of said transformer, said transformer substantially fully charging said condenser only over a plurality of cycles, an X- ray tube connected across said condenser and comprising a nlarnentary cathode, an anticathode, and an auxiliary electrode, and means for impressing on the auxiliary electrode the same potential as that of a portion of the cathode for preventing the passage of current across the tube, and a higher potential for causing the discharge of the condenser.

3. An X-ray installation for making short X- ray exposures, comprising a transformer, a storage condenser, and a rectier connected in series with the secondary of said transformer, said transformer substantially fully charging said condenser only over a plurality of cycles, an X-ray tube connected across said condenser and comprising a cathode, an antioathode and a focussing device for directing the cathode rays on a limited surface of the anticathode, and means for impressing on said device a low potential for preventing the passage of current across said tube, and a higher potential for causing the discharge of the condenser.

ALBERT BOUWERS.

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