US2112080A - Tube rectifier voltage supply - Google Patents

Description

:ch 22, 19538. W, EAMEs 2,112,039

TUBE RECTIFIER VOLTAGE SUPPLY Filed Sept. 19, 1936 WITNESSES: INVENTOR William F. 567/7765.

Patented Mar. 22, 1938 UNITED STATES TUBE ancrmma VOLTAGE SUPPLY Pennsylvania Application September 19, 1936, Serial No. 101,682

2 Claims.

My invention relates to systems of electronic devices, and it has particular relation to automatic means for controlling the supply of energy to the cathode and anode in their proper sequence.

The necessity of pre-heating the cathode of a discharge device before applying anode voltage 'to prevent the destructive effect which would otherwise occur is well known. All devices of this character made according to the teachings of the prior art and with which I am familiar, are complicated in structure and have other disadvantages inherent in their operation.

Discharge devices of the hot cathode gas filled type require that the cathode be heated to its operating temperature before a currentis passed through the device. This is necessary because if a discharge is started with insuificient cathode emission of electrons, the cathode is bombarded by positive ions to efiect release of the additional electrons required. This causes the cathode to disintegrate.

It is accordingly an object of my invention to provide a control system of simple and economic construction for electronic devices, thereby to render their operation more reliable and eiiicient than those of the prior art. 7

Another object of my invention is to provide a novel means for supplying heating currents to the cathode before application of voltage to the anode.

A further object of my invention is to provide automatic means for detaching the anode circuit from the cathode circuit while the cathode is being heated to its operating temperature.

An ancillary object of my invention is to provide a means for preventing the application of anode voltage in case of momentary current interruption in the supply circuit until the cathode is reenergized to its operating temperature.

In accordance with my invention, I have provided a thermal means for delaying the excitation of the anode circuit. A bimetallic strip consisting of two dissimilar metals is provided in conjunction with a relay toisolate the anode from the cathode circuit While the supply current is energizing the cathode circuit. An appreciable interval of time elapses before the thermal device closes the anode circuit and permits the flow of current from a common power unit.

In accordance with my invention, a thermal means is utilized which is rugged in operation and capable of withstanding variations in temperature, with no effect on the overall efficiency. It may appear that the difference between summer and winter temperatures would cause the bimetallic strip used in my apparatus to affect the heating time of the cathode, since heat would be radiated from the heater to the surrounding air. However, the added time required is negligible as compared to the total time and does not aifect the cathode, since the anode is not included in the voltage supply circuit until the added time to the normal period elapses.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims,-the invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description, taken in connection with the accompanying drawing, in which:

Figure 1 is a, diagrammatic view showing a control system in according with my invention.

Fig. 2 is a diagrammatic View showing a modification of my invention as it is applied to a threeelement tube; and

Fig. 3 is a diagrammatic View illustrating the application of my invention to a polyphase system.

The rectifying circuit shown in Fig.1 comprises an electronic device i having a cathode 3 and a plurality of anodes 5. The alternating current to be rectified is supplied from a source H through the primary 1 of a transformer 9 having secondary sections l3 and id. The cathode 3 is supplied With heating current through the secondary section I3.

When the switch ll is closed the supply of heating current to the cathode 3 is initiated and simultaneously a heater I9 is connected across the alternating current source II. The heater [9 is connected in series with a current limiting resistance El and with the normally closed contacts 23 of a relay 25. The relay 25 is an ordinary direct current operated relay with'one make and one break contact.

After a predetermined interval of time, the heater l9 causes a bimetallicstrip 21 of two dissimilar metals welded together, which is heated thereby, to deflect and the free end of the strip to move upward. Contacts 29 and 33 are thus brought into engagement with each other.

It is to be noted that initially no current flows from the cathode 3 to the anode because the return path of the anode circuit 4 is interrupted by the normally open contacts 3! of relay 25. When the bimetallic strip'2l has become heated, the free end closes the anode circuit 4 at points '2933, and thereupon the relay 25 becomes energized and closes its normally open contacts 3|.

Contacts 3! furnish a path in parallel with contact 33 and the free end of the bimetallic strip for closing the circuit between the anode and cathode of the discharge device 1. In addition this contact completes a circuit to the output circuit 39 of the device I. This circuit extends from the plus wire of the output to the midpoint of transformer winding 13 by wires in circuit 2 to the cathode 3, to anodes 5, to transformer winding IE, to the midpoint of this winding and through contacts 3i to the minus wire of the output circuit 39. As the coil of relay 25 is connected across these plus and minus output wires, the coil of relay 25 becomes energized through its own contacts so that when contacts 29 and 33 subsequently open, relay 25 is self energizing.

Simultaneously with the closing of the contacts 3!, contacts 23 open, thus automatically dis connecting the heater element [9 from the alternating current supply H. Thus, the anode circuit 4 is held closed only through the contacts 3| of relay 25.

A safety arrangement is provided so that in case of momentary interruption in the alternating current supply H the anode circuit 4 will be disconnected and the cathode-heating source It will be reconnected. This is accomplished by a self-holding contact 3i of relay 25. Upon the occurrence of an interruption in the voltage supply l, the contacts 3| open and contacts 23 close. Hence, the voltage will not be reapplied to the anode circuit 4 until the cathode 3 is properly reheated as hereinbefore mentioned.

I do not wish to limit my invention to a two element electronic discharge device. Fig. 2 illustrates one application of my invention to an electrionic device 35 having, in addition, a control electrode 31. Direct current relay 25 is in the embodiment shown in Fig. 2 replaced by alternating current relay 26. The latter has an additional contact 39 which is normally open and acts as the self-holding connection in the safety arrangement heretofore described. Contacts 3| in Fig. 1 performed a double function whereas in Fig. 2 two separate contacts 3| and 39 perform the two operations, namely; closing the anode circuit 4 and secondly, reapplying the heating element I9 according to my invention. The output 39 is received through a suitable transformer 4|.

Fig. 3 of the drawing represents an application of my invention to a three phase-system. It is to be noted that only one heater element I9 is required for all cathodes 3 and no additional relay controls 25 are necessary for a single phase system. The operation of a polyphase system is substantially similar to that of the single phase system, hence, explanation is unnecessary.

Although I have shown and described certain specific embodiment of my invention, I am fully aware that many modifications thereof are possible. My invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claims.

I claim as my invention:

1. In combination, a discharge device having an emissive electrode and at least one other electrode cooperative with said emissive electrode to collect the charge emitted thereby, power supply means for energizing said emissive electrode, a source of potential, connections between said source and said electrodes, disconnecting means for interrupting said connections to prevent destruction of said emissive electrode by premature application of potential from said source, timing means to be actuated in response to the initiation of supply of power from said power supply means to said emissive electrode and after being actuated for a predetermined interval of time to actuate said interrupting means to close the connections between said source and said electrodes, said timing means requiring the supply of current for actuation, and means responsive to the flow of current between said emissive electrode and said other electrode for interrupting the supply of current to said timing means while still maintaining the connections between said source and said electrodes closed.

2. In combination, a discharge device having an emissive electrode and at least one other electrode cooperative with said emissive electrode to collect the charge emitted thereby, power supply means for energizing said emissive electrode, a source of potential, connections between said source and said electrodes, disconnecting means for interrupting said connections to prevent destruction of said emissive electrode by premature application of potential from said source, thermal timing means to be actuated in response to the initiation of supply of power from said power supply means to said emissive electrode and after being actuated for a predetermined interval of time to actuate said interrupting means to close the connections between said source and said electrodes, and means responsive to the flow of current between said emissive electrode and said other electrode for interrupting the supply of current to said thermal timing means while still maintaining the connections between said source and said electrodes closed.

WILLIAM F. EAMES.

Images