US1508356A - Electron-discharge device - Google Patents

Description

Sept, 9 1924.

W. C. WHITE ELECTRON DISCHARGE DEVICE Fild' Feb. 18. 1920 Milli-amps- FIQ-Z- 1o 5o+5 m /5 Grid Potential.

Inventor: WI I am C. White A 1 His Attorney.

Patented Sept. 9, 1924.

UNITED STATES 1,508,356 PATENT OFFICE.

WILLIAM C. WHITE, OF SCHENECTADY, NEW YORK, ASSIGNOR '10 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTRON-DISCHARGE DEVICE.

Application filed February 18, 1920. Serial No. 859,680.

To all whom it may concern:

Be it known that 1, WILLIAM 0. WHITE,

a citizen of the United States, residing at Schenectady, in the county of Schenectady,

State of New York, have invented certain new and useful Improvements in Electron Discharge Devices, of which the following is a specification.

The present invention relates to the operation of electron discharge devices and comprises also an electron discharge device having novel structural features adapting the same particularly for operation in accordance with my invention.

In one of its aspects my invention comprises a method of detecting signals by operating an electron device at a cathode emissivity and electrode voltage so related that all of the electrons emitted by the cathode are utilized and so operating a control electrode that both a decrease and an increase of potential on the control electrode produces a decrease of current in an anode circuit in which a detector may be connected.

The above and other aspects of my invention will be pointed out with greater particularity in the appended claims.

The accompanying drawings show in Fig. 1 a novel electron discharge device especially adapted to carry out my invention; Fig. 2 is a diagram of a radio-receiving system embodying my invention; and Fig. 3 is a curve illustrating the electrical characteristics of a device when operated in accordance with my invention.

Referring to the drawing, and particularly to Fig. 1, the electron discharge device comprises a cathode 4 consisting of suitable refractory material such, for example, as tungsten connected to leading-in wires 5, 6, sealed into the stem of a bulb 7. Adjacent the cathode is an anode 8 and a charge-controlling electrode 9, respectively, connected to the conductors 10 and 11, which are sealed into the bulb 7. The control electrode 9 preferably has a materially larger surface than the anode 8. With this object in view the electrode 9 preferably is made cupshaped and surrounds the cathode while the anode is rod-shaped and is located within the cathode. The space within the bulb 7 preferably is evacuated and the parts of the device preferably are free from gas to such extent that a discharge may occur between the electrodes without appreciable gas ionization.

In the system shown in Fig. 2, the electrode 9 and the cathode 4 are connected respectively by the conductors 12, 13 to the secondary of an air core transformer 14, the primary of which is in circuit with an antenna system 15. In circuit with the electron device is a battery 16 across the terminals of which is connected a resistance 17 to which an adjustable potentiometer connection is made by the contact 18. Con-' nected across the conductors 12, 13 is a variable condenser 19. A detecting device 20, for example, a telephone receiver, is connected by the conductors 21, 22, to the oathode 4 and the anode 8 in circuit with a battery 23 shunted by an adjustable resistance 24.

The voltage between the cathode and the anode furnished by the battery 23 should be relatively low, say, several volts, and the cathode temperature should be so adjusted that at this voltage, commonly called the plate voltage, the electron current is limited by the electrons emission of the filament. In other words, the total electron current should not be susceptible of increase by an increase of voltage between the cathode and the cooperating positive electrodes, a condition which is commonly designated as saturation current.

When the voltage in the circuit 12, 13, commonly called the grid voltage is adjusted to make the electrode 9 slightly positive with respect to the cathode 4, a plate current will flow in the circuit 21, 22. This current, as shown in Fig. 3, will decrease when the grid voltage becomes either more positive or varies in the negative direction, that is, becomes less positive or passes through zero and becomes negative.

In Fig. 3 the current in milliamperes flowing in the plate circuit 21, 22, has been plotted as ordinates against the grid volts as abscissae, the grid volts being plotted negative and positive on either side of zero voltage indicated by a dotted line. When the potential of the electrode 9 changes in a negative direction, less current will flow from the. cathode to the anode as the negative voltage established by the electrode 9 retards the electrons from the cathode to the anode. When the grid becomes more positive some of the electrons which would tend to move from cathode to anode are attracted to the grid 9 and as the emission of electrons from the cathode is limited by the temperature of the cathode the current to the anode must decrease. Therefore, audio groups of radio frequency impulses impressed upon the electrode 9 from the transformer secondary 1a will cause a diminution of average current in the plate 21, 22, and an audible note of the group frequency in the telephone receiver 20.

It is not absolutely essential in the practice of my invention that the controlling electrode 9' should be located outside the cathode, but this construction enables the controlling electrode 9 to be given most conveniently a larger surface than the anode which is located within the spiral cathode filament. Modifications will readily suggest themselves for securing this preferred function in some other manner. .In fact, the benefits of my invention may be obtained by operating the cathode of any of the three electrode electron discharge devices at such temperature that the plate current will be limited by electron emission at a given plate voltage and suitably adjusting the grid voltage so that an increase or decrease of the grid voltage will produce a decrease of plate current. However, when using the construction in which the surface of the grid is not relatively large with respect to the surface of the anode plate, current change produced in this manner will not be so marked and the characteristic of the tube will not be so sharp as when using a construction, as shown in Fig. 3 of the accompanying drawing.

What I claim as new and desire to secure by Letters Patent of the United States, is 2-- 1. An electron discharge apparatus comprising a cathode adapted to emit electrons, a controlling electrode located about said cathode and within electron-receiving relation thereto, a cooperating anode enclosed by said cathode, a source of energy connected between said cathode and said anode, means for charging said controlling electrode to a positive potential with respect to said cathode, means for impressing potential variations upon said controlling electrode, and a source of current connected between said cathode and anode having a voltage sufliciently high to produce saturation current.

2. An electron discharge device comprising a cathode adapted to emit electrons, a cooperating anode, a controlling electrode having a greater surface than said anode, located in electron receiving relation to said cathode, means for charging said controlling electrode to a positive potential with respect to said cathode, a source of current connected between said cathode and anode having a voltage sulficiently high to produce saturation current, and at detecting device in said anode circuit. 0

3. A radio detector comprising a spiral cathode adapted to be heated to incandescencc, an anode located within said cathode, a control member having a greater surface than said anode located about said cathode and separated therefrom only by a vacuous space, means for charging said controlling electrode to a positive potential with respect to said cathode, a source of current connected between said cathode and anode having a voltage sufliciently high to produce saturation current, and a detecting device in said anode ciccuit.

4. The method of operating an electron discharge device comprising a cathode adapted to emit electrons, an anode and a controlling member adapted to receive potential variations which consist in impress: ing a current at substantially constant volt age between said cathode and anode, adjust ing the electron emissivity of the cathode to operate at a saturation current value at said voltage, charging said controlling member to a voltage at which the current between said cathode and anode is a maximum, and impressing voltage variations to be detected upon said controlling member.

5. The method of operating an electron discharge device comprising an electron emitting cathode, an anode, and an electrostatic control*electrode to detect groups of high frequency oscillations which consists in impressing a voltage between said cathode and anode sufficiently high to substantially utilize all of the electrons emitted by said cathode, charging said control electrode to a positive potential at which the current in the anode circuit is a maximum, and impressing the oscillations to be detected upon said control electrode thereby producing diminutions of current in the anode circuit corresponding to the respective groups of high frequency oscillations.

6. An electron discharge device comprising an anode, a cathode adapted to be heated to incandescence, a cooperating electrode spaced in electron receiving relation about said anode and cathode, means for charging said cooperating electrode to a positive potential with respect to said cathode, a source of current connected between said cathode and anode having a voltage sufficiently high to produce saturation current, and a detecting device in said anode circuit.

In witness whereof, I have hereunto set my hand this 16th day of February 1920.

WILLIAM 0. WHITE.

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