US2215744A - Roentgen apparatus - Google Patents

Description

Sept. 24, 1940. K. SILBERMANN 2,215,744

ROENTGEN APPARATUS Filed Aug. 26. 1938 lnvenzor: iar' 55656/77212/212/ Patented Sept. 24, 1940 UNITED STATES 2,215,744 A ROENTGEN APPARATUS Karl Silbermann, Erlangen, Germany, assignor to The firm Siemens-Reinliger-Werke Aktiengesellschaft, Berlin, Germany Application August 26, 1938, Serial No. 226,906 In Germany September 27, 1937 5 Claims.

This invention relates to Roentgen, apparatus, and is particularly concerned with a device for controlling the transition from the fluoroscoping to the radiographing operations, and vice versa.

The use of such a device is desirable because of the fact that the anode current is considerably higher during the period of radiographing as compared with the period of fiuoroscoping, necessitating an increase in the temperature of 1 the glow cathode during radiographing over the value required for fiuoroscoping. The radiographing cannot commence immediately at the moment of terminating the fiuoroscoping operation, because a certain time interval or prepara- I5 tory period is required for the heating of the cathode to the requiredvalue, in view of the inertia of the filament. A like preparatory interval is, of course, also requiredfor the transition from radiographing to fluoroscoping, with the differ ence that time must be given to reduce the temperature of the cathode.

A brief review of the state ofthe art is given below for the purpose of facilitating the understanding of the detailed description which is to follow.

In order to prevent premature radiographing, the suggestion has been made to equip the timing switch provided for controlling the exposure period with an additional arm or contact finger which starts its operation with the connection of the heating current for radiographing and engages the radiograph exposure contact finger (radiograph release) when the cathode is sumciently heated, thus initiating the exposure. The drawback of this arrangement resides in the relatively expensive and specially made timing switch and associated equipment which is required. A

further shortcoming resides in the fact that this arrangement prevents only an objectionable quick transition from fluoroscoping to radiographing, without furnishing any safeguard for the reverse operation. This is a disadvantage, because the temperature of the incandescent cathode when heated to its radiographing valueis so high that upon premature or too quick transition to fluoroscoping, the anode current is a multiple of the usual or required value at the moment of closing the anode circuit for fluoroscoping. The high current causes excessive irradiation of the fiuoroscope image, which handicaps the work of the operator. If such control is used in apparatus of the rotating anode type, the anode of the tube may be damaged by excessive current at the start of fiuoroscoping,

because it does not rotate during this period. The meter for the anode current, which is switched to decreased measuring range for fluoroscoping operation, may likewise be damaged by excessive current. 5 The above mentioned drawbacks are avoided by the invention according to which a delay means, for example, a suitable slow-acting relay is used, causing automatic completion of the anode circuit of the Roentgen tube for fiuoroscoping or for radiographing a short period after closing the tube heating circuit for the corresponding operation. The required delay between the closure of the heating circuit and the closure of the i anode circuit may be adjusted, for example, to about half a second, and may be obtained in any suitable manner, for example, by equipping the relay with an air brake or a hydraulic dash-pot. Mercury switching tubes may also be very advantageously used for this purpose.

The invention will now be described with reference to the accompanying drawing, showing an example of a practical embodiment in diagrammatic representation.

The anode circuit of the Roentgen tube I is supplied with current from the secondary winding 2 of the high tension transformer 3. The heating transformer 5 serves for heating the cathode 4 of the tube l. The proper adjustment of the heating current for radiographing is obtained by means of the resistance 6, and for fluoroscoping by means of the resistance 1. Current is supplied to the primary winding of transformer 3 for radiographing by means ofthe switch 8, and for fiuoroscoping by means of the switch 9. These switches are actuated by electro-magnets l0 and II, respectively. Magnet I0 is operatively connected with the master control switch [2 in position A, which is the radiographing position, under control of the timing switch IS. The magnet H is operatively connected with the master control switch I2 in position D, which is the fiuoroscoping position. The master control switch I! is manually operated.

The slow-acting relay [4 permits the operation of relay I I, when it is desired to fluoroscope after completing the radiographing, only after the cathode 4 has sufficiently cooled down; and, vice versa, prepares the apparatus for radiographing only after the cathode has been raised to the required temperature.

The sequence of operations is as follows:

Assuming that main switch 2| is closed, the switch l2 may be operated into the position D potential for radiographing.

(for fiuoroscoping), whereupon relay l4 energizes. This relay actuates its armature l5, and bridges the contacts I6 and Il, thereby closing the circuit for magnet H, which energizes and completes the primary circuit oftransformer 3 through a resistance and thus provides the proper anode potential required for fiuoroscoping. This operation is delayed as compared with the closure of the tube eating circuit (switch l2, left hand side, position D), due to the slow-acting feature of relay M, which may be equipped with an air or hydraulic dash-pot l8. A delay of about half a second is sufiicient for adjusting the temperature of the cathode to'the value required for fluoroscoping.

If it is now desired to radiograph and the apparatus is quickly switched to the corresponding position (switch l2, position A), the armature I5 is released with delay, and when it reaches its alternate position, it bridges the contacts l9 and 25, thereby actuating the timing switch 13, which causes operation of relay in and closing of switch 8. This switch closes the primary circuit of the transformer 3 through a, tap switch adjusted to provide the proper anode Again, as in the previously described case, the anode potential is supplied only after the cathode l has reached the temperature required for this particular operation under the control of resistance 6, which has been connected in position A of switch i2 shown at the left side of the drawing.

The initially described operations take place if it is desired to repeat the fluoroscoping operation; that is, the switch I2 may be operated to position D, closing the proper heating circuit for the cathode over resistance l, and relay M is operated to supply the corresponding anode potential after a certain time interval sufficient to permit the cathode 4 to assume the proper temperature.

Numeral 2i designates the main power switch, and 22 the connection to the power source, which may be the usual commercial power supply.

Changes may be made Within the scope and spirit of the following claims, wherein I have defined what I believe to be new and What is desired to have protected by Letters Patent of the United States.

What is claimed is:

1. In a Roentgen apparatus, a Roentgen tube, a master control switch having a fiuoroscoping position and a radiographing position, cathode and anode circuits suitable for fiuoroscoping established in the first position, cathode and anode circuits suitable for radiographi-ng established in the second position, and means effective whenever the position of said switch is changed for automatically delaying the establishing of the anode circuit corresponding to the new position of the switch, thereby providing time for the cathode to assume the temperature at which it is maintained by the cathode circuit corresponding to such new position.

2. In a Roentgen apparatus, a Roentgen tube, a master control switch, a heating circuit for the cathode completed by operation of said switch, a relay for closing the power circuit over which anode potential is supplied, a circuit for said relay prepared by the said switch operation, and means responsive to said switch operation for completing the circuit of said relay after a predetermined time interval.

3. In a Roentgen apparatus, a Roentgen tube, circuits for supplying difierent values of heating current to the cathode of said tube, circuits for supplying different anode potentials to the anode circuit of said tube, relays for closing said last mentioned circuits, a master control switch for closing either heating circuit and for determining which of said relays is to be operated, and time delay means for operating the selected relay.

4. In a Roentgen apparatus, a Roentgen tube, two cathode circuits for said tube arranged to provide two difierent values of heating current suitable for fluoroscoping and radiographing, respectively, a master control switch for closing either of said circuits at will, two circuits for supplying two different anode potentials to said tube suitable for fluoroscoping and radiographing, respectively, separate closing devices for said anode circuits, means included in said master switch for preparing a circuit for the proper closing device each time a cathode circuit is closed, and means controlled by said master switch for completing the prepared circuit after a predetermined time interval.

5. In a Roentgen apparatus, a cathode circuit, a switch for varying the amount of current flowing in said circuit, an anode circuit and source of potential therefor, said switch having contacts for interrupting the supply of potential to said anode circuit each time the value of the current in the cathode circuit is decreased or increased, and means eiiective automatically a predetermined interval after a change in the cathode current for re-establishing the anode potential.

KARL SILBERMANN.

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