US2460455A

US2460455A - Electronic circuit

Info

Publication number: US2460455A
Application number: US720229A
Authority: US
Inventors: Wilmina L Hurley
Original assignee: WILMINA L HURLEY
Current assignee: WILMINA L HURLEY
Priority date: 1947-01-04
Filing date: 1947-01-04
Publication date: 1949-02-01
Anticipated expiration: 1966-02-01

Description

Patented Feb. 1, 1949 UNITED STATE s PATENT oFFIcE ELECTRONIC omourr ville, 111.

Application January 4, 1947, Serial No. 720,229

2 Claims.

1 This invention relates to a means for deionizing a gas-filled tube once it is ionized. It particularly relates to an electronic circuit in which a vacuum tube is connected inseries with a gas-filled tube,

rent potential thatonce it is i0nized,it will con- :1

tinue to ionize until the circuit is broken regardless of how negative in potential the control grid is driven. In the prior art, mechanical switches, time delay relays and other mechanical devices have been used to interrupt the circuit. However,'

mechanical switches and the like, or anything involving mechanical means for interrupting the circuit, have the disadvantages that are inherent in all mechanical means. Mechanical means are never as instantaneous in their reaction as electronic means. Mechanical means require more upkeep and if a switch sticks, the desired result is not obtained. There is nothing to go wrong with electronic means such as is described herein. Electronic means are instantaneous and will always respond in the required manner.

Broadly my invention comprises connecting the gas-filled tube in series with a vacuum tube across a source of direct current potential. 'The flow of currentthrough the vacuum tube is accomplished by the control of a control grid in the vacuum tube. The control grid in the vacuum tube will control the now of current through the circuit and if sufficient negative potential is placed on the control grid in the vacuum tube, the vacuum I tube will cease to conduct and'in 'efiectbecomes an electronic circuit breaker. The device will work equally well whether the vacuum tube is in the plate circuit of the gas-filled-tube or is in the cathode circuit of the gas-filled tube.

It is therefore an object of this invention to provide an improved means-for breaking the circuit of a gas-filled tube which has once ionized by employing a vacuum tube in series with a gasfilled tube.

Other advantages, objects and uses of my invention will become apparent byreferring to the drawin s in which Figure 1 illustrates a circuit with the vacuum tube in the anode circuit of the I as-filled tube.

- the resistor 20.

Figure 2 illustrates a' similar circuit with thevacuum tube in the cathode circuit of a gas-filled tube.

For sake of illustration the drawings are described in connection with photoelectric inspection operation although my invention will apply equally well to any operation where the gasfilled tube is ionized by appropriate means and when it is desired-to deionize the tube, a negative potential is placed on the control grid in the vacuum tube.

Referring to Figure 1, a gas-filled tube I0 is pro vided having an anode circuit II, a cathode circuit I2 and a control grid I3. Vacuum tube I4 .is connected in the anode circuit I I in series with the'gas-filled tube Ill. The vacuum tube I 4 has a cathode circuit I5, an anode circuit I 6 and a control grid I1. The two tubes I0 and I4 are connected in series across a direct current source of potential in which the positive terminal of the direct current source is at I8 and is grounded at I9. In the particular illustration of Figure 1, the control grid I3 is controlled photoelectrically by the amount of light received by the phototube I9. The phototube I9 is connected in series with the resistor 20 across a source of direct current potential having its positive terminal at 2! and its negative terminal at 22. The control grid I3 is connected at 23 between the phototube I9 and When the phototube It is in shadow, the control grid I3 is more negative than the cathode I2 and the gas-filled tube I!) will not conduct. However when the phototube I 9 receives light, a positive potential is placed on the control grid I 3 and if at the same time the positive potential is placed on the control grid I'l, current will flow through the circuit employing the tubes l0 and I4. Once the tube I0 is ionized by such a condition, the control grid I3 will no longer be able to control the flow of current through the circuit although the tube I 9 is placed in darkness, because this is a characteristic of a gas-filled tube as has been heretofore explained. However, the flow of current through the circuit from the point I 8 to the point I9 can be stopped if the potential on the ground grid I1 is changed from positive to negative. In other words, the control grid I1 is effective at any time for stopping the flow of current through the circuit where as the control grid I3 can function only to initiate the flow but cannot stop the current once the tube III is ionized. The particular manner of controlling the control grid is immaterial to'my invention. The control grid could be com nected'to a switch. which would alternate from a conduct.

positive potential to a negative potential. However in the illustration given, the control grid ll is also controlled photoelectrically. This" is done as follows: r

A second vacuum tube 2% is provided having a control grid 25, an anode circuit 25, and a cathode circuit 21. The tube E i is connected in series with a load resistor 28 and a biasing resistor 29 across a direct current source of potential having its positive terminal at 3B and its negative terminal at 23%. The control grid ll of the. tube It is connected to the point 32 between the resistor 28 and the tube 2 By such a connection the tubes and 25 are 186 out of. phase; That is when tube 24 is conducting, tube M is rendered non-conducting and when tube 25 is non-conducting, tube I2 is conducting. The bias on the tube 25 is controlled by a photoelectric circuit employing the phototube 33 connected in series with a resistor ii -i across a direct current source of potential having its positive terminal at 35 and its negative terminal at 35. The control grid 7 25 is connected between the phctotube 33 and the resistor at point When the phototube $3 is in darkness a negative potential is placed on the control grid 25 so that the tube 25 will not If the tube 24 does not conduct, a positive potential is placed on the control gird ii and the tube M is placed in condition for conducting a current. When the phototube 3'3 receives light, a positive potential is placed on the control grid 25 so that the tube 2 3 will conduct'and because of the load resistor 28, the control grid 57 is driven negative and the tube M is placed in a condition so that it will not conduct a current.

In the anode circuit l l is a relay coil 38 which actuates a relay switch 39. The relay switch is shown in the open position which is the condition when no current flows through tube it; The relay switch may actuate a motor or any other suitable mechanism which is desired The operation of the device is as follows: When the-tube 33 is in darkness, thetube 21% will not conduct and a positive potential is placed on the grid ll. This is the normal condition of the bias on the grid ii. For any operation regardless'of no particular means for controlling the bias on the grid ii, the grid ll'is'normally maintained positive and whether or not the current will flow through the circuit from the point. [8' to the point 39 depends on the bias of the control grid When the control gird i3 is driven positive by tube it receiving sufficient light, currentwill flow from point it to point :9 and will continue to flow until the control grid i? is driven negative by the photocell 33 receiving light regardless oi .the condition of light on tube it.

. necting a circuit employing a choke coil 38 and a resistor ll in parallel with the gas-filled tube it. It has been found that there is a gradual tapering off of the amount of current that the tube it will conduct when a negative bias is placed i want it distinctly understood that the par- However, it is pnon the control grid ii and where it is desired to,

immediatelystop the flow of current throfig lhfi function of always conducting the current it is set for and in eflect what the choke coil ill does isto take'all of the current from the positive terminal l8 and conduct it to ground when a negative potential is placed onthe grid 1?. This has the efiect of immediately stopping the flow of current throu'gh'tube l6 whereas otherwise there may be a small amount of current flow through tube 53 for a short time which is undesirable in some operations, The amount oi currentthat a choke coil to will always conduct depends upon the point of adjustment of the adjustable resistor contact 5-2. The choke coil Ml itself has no control on the. device but the minute the grid l? is driven sufficiently negative that the choke coil will conduct all of the current from point It to point it, the tube ill will cease to conduct. The choke coil therefore has the effect of immediatelystopping the flow of current through the tube ill when the current through the tube M reaches a certain minimum. The choke coil has many advantages in operations where it is desired to immediately break the circuit sot-hat tube ill will not conduct.

The choke coil circuit embodyingthe choke coil til and the resistor 4 l is connected in parallel with the'tube H] by connecting the circuit from point 43' to the ground l9.

Figure 2 is similar toFigure 1. The only real difference is that the tube i4 is in the cathode circuit of the tube ill rather thaninthe anode circuit. The operation of the device in Figure 2 is substantially the same. The circuit employing the choke coil 40 and the resistor ll is connected in parallel with the tube it by having it connected from the point 53 to the point :6. The vacuum tube l4 serves substantially the same function whether it is connected in the anode circuit of the tube ill or connected in the cathode circuit of tube ill.

Throughout the specification and claims when ever I speak of a positive or negative potential, or a positive or negative bias, I mean the relative potential or bias of the control grid in respect with its cathode; The cathode and grid may both be at a positive potential but if the grid more positive than the cathode, apositive bias or potential is placed on' the grid. Likewise both may have a positive potential but if the grid is less positive than the: cathode, arelativeiy negative potential is placedon the grid.

I claim as my invention: 1

1. An electronic circuit comprising'a source of direct current, a first series circuit connected to said source comprising a vacuum amplifying tube and a gas-filled amplifying tube, each of said tubes having an anode circuit, a cathode circuit and a control grid, 2, second series circuit corn prising a choke coil and a resistor connected in parallel with the gas-filled amplifying tube, the control grid of said vacuum tube being normally biased so as to enable the vacuum tube to conduct a current, independent vo1tage-applying means controlling the bias on the control grid of the gas-filled tube thereby controlling the ionization of the gas-filled tube and means for preventing or stopping the flow of current through the gasfille'd tube including voltage-applying means for placing suflicierit negative bias on the control said third amplifying tube such that the two tubes are 180 degrees out of phase, the control grid of said third amplifying tube normally biased so as to enable the vacuum tube to conduct a current, independent voltage-applying means controlling the bias on the control grid of the gasfilled tube for controlling the ionization of the 6 gas-filled tube, and means for preventing or stopping the flow of current through the gasfilled tube including voltage-applying means placing sufficient positive bias on the control grid of the third amplifying tube which renders the vacuum tube non-conducting.

SAMUEL C. HURLEY, JR.

REFERENCES CITED The following references are of record in the his of this patent:

UNITED STATES PATENTS Number Name Date 2,124,848 Powell July 26, 1938 2,356,195 Balsley Aug. 22, 1944 2,404,754 Simpson July 23, 1946