US2587290A - Electronic pulse-power supply - Google Patents

Description

IMEE O g I 25 M v g H. ,1. DAILEY ET AL ELECTRONIC PULSE-POWER SUPPLY Filed Jan. 27, 1945 Feb. 26, 1952 T0 EXHAUS INVENTORS. /7.J? Dfi/AEY J. J. BUZZ/N WWW ATTORNEY Patented Feb. 26, 1952 UNITED STATES PATENT OFFICE ELECTRONIC PULSE-POWER SUPPLY v Hampton J. Bailey,- Bloomfield, and John J. Borzin, Newark,; N. J., assignorsto. Westing: house Electric Corporation, East Pittsburgh, Pa, a corporation of Pennsylvania Application January 27, 1945, SerialNo'. 574,918

3 Claims. 1 In exhausting vacuum devicesv of the electrical art such as lamps and radio tubes, one'of the maimproblems is the removal of gases in the various parts of the: electrical device. The rate of' gaswvolu-ti'on from such a device part is a tunction-of-th'e.temperature of thepart. The higher'the temperature,- the more rapid is the g evolution; However,- in attempting to out-- an electricalvacuumdevicait is found that li-rnit'to-the temperature at'which the an be held steadily. This limit is -u'sually M he'--maximum :average dissipation which 'antlle'd safely without destroying the device-being exhausted. Such temperature is asuauy arouna 1-200 CL to l500-'C.

It liasbeeirfound, however, that if the electrical vacuum device parts can be raised to a temperature far exceeding the maximum permissible-steady temperature, but accomplished intermittently '-for-'relat-ive1y short intervals of time-{that damage is avoided, whereas the rate of-gas-removal is increased severalfold. Go'h-trol of the length of "pulse, interval between pulses, variation due to gas condition of the electrical evacuateddevice, and other considerations assume importance in the utilizationof the inter mittent application of heating current.

The invention accordingly has-for its objects a realization of the aforementioned intermittent application of heating current with the controls indicated.

'O'ther-objects-cf the inventionwill appear to those skilled in the art to which the invention apperta'i-ns; both -by direct recitation thereof and by'implica tion from the context-as the descrip tion proc'eeds.

Ref errmg --to the'accOmpan-ying drawing, Fig ures'l and z t-hereof show two circuit arrangemerits embodying the present invention.

In aiddrawing, the electrical vacuum device, here shown"as a radio tube, is designated by numeral l0 and is-the device the gas removal from which is accomplished by the-present invention. The apparatus constitutingthe physical. embodiment of the invention provides output terminals-X and Y to which appropriate con nection may conveniently be made to the said electrical vacuum device. Input connection from -a commercial line or other source ofaIternating current for supplying the-heatingcurrent to; output terminals X and Y, is designated-as zinput tern'iinals Aband -B.- Full wave rectification of theicurrent betweeninput A, B and output X, -Y, is provided, a bridge rectifier R beingshown in Fig. 1, anda-centertap rectifier R being-shown in Fig. 2. In each instance a transformer T is provided,- the secondary ll of which is in series with the anode-cathode path through two triode electronic devices l2,- forming part of and situated at the-positive end of the rectifier. Flow of current through said anode-cathode path is under control of grids l3 of said triode electronic devices. Preferably said triode electronic-devices arethyratrons, a characteristic-of which is sharp cut-off by. grid bias. Thustheduration of current -flow from input A, .B to output X, Y, and recurrence of the pulses are determined by the grid bias of'the thyratrons, and the automatic control of jthatgrid bias constitutes a feature of the present invention.

Describinginsdetail the preferred embodiment of the invention and showing of Fig. 1, it may be added that the main line rectifier R shown provides, in conjunction with the thyratrons l2, 1a pair'of one-wayelectrical valves I4 of which crystals, =-copper oxide coated plates, and diode vacuumtubes are -examples. The anodes I5 of these valvesyare connected, as by wire I6, and from that wire is a circuit wire I! to output terminal 3!. The cathodes [8 of said valves M areconnected :to the ends of the transformer secondary I I and tothe anodes'of the thyratrons. The cathodes l9 of the thyratrons l2 are con- -nected,-as by wire 20, andleading therefrom is the other main circuit wire 2! to output termina-LX.

The thyratron grids l3 are connected by a wire :22 in which two grid resistors 23 are interposed, :each between a: center tap '24 and one of said grids. Fromsaid center tap 24 a wire 25 makes ponnectiomwith the anode 2.6 of. another onecircuit transformer 30.

way valve 21 which for convenience will be referred to as the grid-control valve. A line 28 :leadsafrom the cathode 29 of said grid-control valve .2! toone end of the secondary of a timer- The load on this timercircuit transformer secondary is a condenser 3| rconnected atone side'by wire 32 to the secondary at the'end away from the'grid control valve 21 F .and connected at its otherside to the line from off periods of two to three.

selected so that the charge on condenser 3| will be adequate for making the thyratron grids negative to and beyond their cut-off value. Heating current to the tube or other electrical vacuum device being out-gassed is thereby interrupted.

In the primary circuit of timer-circuit transformer 30 is a timer 33 of suitable construction, various makes being available on the market, and function of which is to repeatedly open and close the circuit in a constantly recurring cycle of current from the alternating current line feeding the primary of said transformer. When the timer 33 closes the circuit to the transformer, charge on the condenser takes place immediately, the thyratron grids are negatively biased and heating current to the electrical evacuated device is interrupted. When the timer breaks the supply circuit to the transformer 30, charge on condenser 3| dissipates through a resistance 34 in parallel with the condenser, thereby eliminating the negative bias on the thyratron grids and again permitting flow of heating current to the electrical evacuated device. It will now be clear that the construction provides for a flow of heating current when the timer circuit is open or non-conducting, and conversely, a stoppage of heating current when the timer circuit is closed or conducting.

It should be borne in mind that the limitation of permissible temperature for steady heating of the electrical device being out-gassed of 1200 C. to 1500 C. necessitates long periods of heating and evacuation. According to the present invention, short pulses of much higher temperature are applied to the said device, namely such temperatures as 2000" C. to 2200 C., with interposed off pulses of the heating current, and with the timer adjusted to apply the pulses at a rate at which the average dissipation of heat in the device being treated is within the capabilities of the device to accomplish without detriment. Satisfactory results have been attained in practice by utilizing a ratio of on to The timer is, however, adjustable and this ratio may be changed.

A feature of the invention furthermore contemplates inclusion of load-sensitive means for automatic protection against excessive heating current being applied while or when the device being treated is excessively gassy. Presence of excessive gas causes the device to draw more cur-- rent, and this is taken advantage of as a control means for interrupting the said current. In the line 2| from the thyratron cathodes I9 to the output terminal X is provided a variable resistor 35, and between the resistor and said terminal X is'connected a cathode 36 of an electronic control device 3'! which is preferably a thyratron. The anode 38 of said electronic control device 31 connects to one end of the secondary of a transformer 39, the other end of said secondary being connected to the previously described secondary of the timer-circuit transformer and therefore connected to the dissipating resistance 34 and condenser 3|. There is a similar resistanoe 40- to dissipating resistance 34 in series therewith and extending from wire 32 to the main line circuit wire 2| between rectifier T and the above mentioned variable resistor 35. The two said resistances arein seriesand constitute an electrical cross connection from wire 25 to main line circuit wire 2|. In parallel to the resistances 34 and 40 across these same two wires 25 and 2| is a condenser 4|.- From the vicinity of connection of the main current wire 2| and resistance 40 is a lead wire 42 to grid 43 of the electronic control device or thyratron 31, a source of potential, such as battery 44 being in series in said lead wire with the negative end toward the grid. This negative potential normally suffices to bias said grid 43 to cut-off so that no current flows in the cathode-anode circuit thereof. However, an excessive current to the electric device being degassed, due to execessive gas, for instance, and developing high voltage drop across variable resistor 35 then causes a positive or less negative bias on the grid 43 of the control device 31, which renders the cathode-anode circuit thereof conducting. This, in turn, through the combination of applied alternating current voltage from transformer 39 and control device 37 acting as a rectifier applies a negative charge on condenser 4| and negative bias to the grids l3 of thyratrons l2 of the main heating supply rectifier R to cut-off, and thus interrupts the heating supply current to output terminals X, Y. As soon as power is removed from the device being degassed, the voltage drop across variable resistor 35 disappears, control device 31 becomes non-conducting, condenser 4| discharges through resistors 34 and 40, and the negative bias is removed from the main rectifier thyratrons l2. Those thyratrons therefore become conductive and power is reapplied to the electrical evacuated device In on exhaust. As long as the excessively gassy condition of that device I0 prevails, the recurring on-oif operation of control device 31 continues. But as soon as the excessively gassy condition clears up, the control device 31 is no longer rendered conductive and ceases to function actively to interrupt the heating current, and timer 33 acts to pulse the heating current. Condenser 4| across the grid-cathode circuit of the thyratrons of the main rectifier R will function to stabilize the operation of those thyratrons, and grid resistors 23 in series with the grids of those thyratrons will function to prevent the thyratrons from drawing excessive grid currents.

Referring now to the disclosure of Figure 2. main line rectifier R is shown with its power transformer T having a center tap for one main line H to output terminal Y. Said rectifier R also having two triode electronic devices |2 func-. tioning as rectifier tubes and having grids l3 for control or cut-off purposes as above described. The cathodes IQ of these devices are joined ,by wire 20 from which leads a wire 2| to the other output terminal X. A biasing resistor 35a is included in connection 2|. In shunt with-the biasing resistor 35a is a line 4'! in which is in? cluded a condenser 48, a one-way control valve 49 and one section 50 of a voltage divider ree sistance 5|, whichin its entirety connects across the main lines I! and 2| between output terminals X and Y. The one-way control valve 49 may, as indicated for similarly illustrated devices l4 and 21 of the showing of Fig. 1', be any desired instrumentality such as a, crystal, copper oxide coated plates or a diode electronic vacuum tube. It is arranged with its anode 52 connected to the condenser 48 and its cathode 53 to the voltage divider 5|. Between said condenser 48 and said one-way control valve 49, a line 54 is connected which leads to the grids of rectifier triodes or thyratrons |2 of rectifier R; This line 54 includes a variable resistor 55 beyond which is a cross connection 56 bridging condenser 48 back to shunt line 41 and including a second condenser 51 which consequently is in electrical parallel to the first-mentioned condenser 48. At the opposite side of the second condenser 5! to variable resistor 55, and therefore having direct connection to the thyratron cathodes I9, is a resistance" 58 beyond which is one branch 59 to a third condenser 60 andanother branch 6| to a variableb-ias-discharging resistor 62, the other sidesof said third "condenser :60 and biasdischarging resistor 62 being connected by wire-63. This Wire 63 also-hasa connection 64 back to shunt line 41, connecting therewith between oneway val-ve 49- and -variable resistor 55. Said connection 64-includes-thereinanother one-way valve 65 of suitable character and arranged with its cathode 66 toward-'the-a-no'de of the previously described one-way valve 49' and with its anode t l towa'rd the condenser-var-rableresistance cor-inection 63. A bias discharging electronic device 68; which-is preferably athyratron having cathode '69, anode Wand grid 'H'Qhas it's'cathode connected to the line 54 to the grids of the power rectifier thyratrons through a biasing resistance 12 in that line, has its anode connected to line 6| at one end of bias discharging resistor 52 and has its grid connected to line 63 at the other end of said bias discharging resistor 62.

In operation, power rectifier R. applies full-' wave rectified current to main lines I! and 2|, a portion thereof passing through the voltage divider resistance 5| including section thereof. Due to shunt line 41, part of the current passes through that line and part through biasing resistor 35a. First condenser 48 is charged almost instantly through one-way valve 49 to the voltage developed across said resistor 35a minus the voltage drop in rectifier 49. The voltage across this first condenser 48 then starts charging the second condenser 51 through variable resistor 55. The voltage across the first condenser 48 also charges the third condenser 65 by way of 4 connections 63, 64 and the second one-wayvalve 65. The polarity of the voltage on the side of the condensers having connection 54 to the power rectifier thyratron grids I3 is negative. When the potential across the second condenser 51 has risen to sufiiciently high voltage, the negative charge biases the power rectifier thyratron grids beyond cut-off, and since the thyratrons then are non-conducting, the power supply is interrupted in main lines I! and 2| to outputs Y and X respectively. As indicated, charge on the first condenser 48 exceeds that needed by the second condenser 51 for cut-off of the thyratrons before cut-ofi takes place, and after cut-01f is efiected, the excess charge continues to increase the charge on the second condenser 51. This action can give a time delay for the off period and is subject to increase or decrease by adjustment of variable resistor 55 between the two condensers. One-way valve 49 prevents first condenser 48 from discharging back through biasing resistor 35a.

During the charging period grid H of the biasing thyratron 68 is made negative so that thyratron is non-conductive, and the third condenser may then be and is also charged through the second one-way valve and connections 64 and B3 and through the first oneway valve 49 in series therewith. When the thyratrons I2 of the power rectifier are blocked by the negative bias applied to their grids l3, the third condenser begins discharging through variable bias discharging resistor 62, and when this voltage decreases suificiently to render grid II of biasing thyratron 68 adequately more positive toibringsit.belowrcuteofi, said thyratron :68 will: Ifirie or become conductivein its cathodeanode circuit. and instantaneously. removes the charge from the several-condensers (condenser 51. in; particular), and. the bias from the grids [3 of the power rectifier thyratrons. Power may then again flow to'the output KY and there fore ito the electric evacuated device being outgassed applied thereto as in Fig. I. This; structureaccordingly replaces'use' of a timer and its additional external circuit connection to the power source, and in-addition. to automatically pulsing thev applied power, accomplishes ltimed cut-ofi? and reapplication of the heating current. Adjustment of variable resistor 55 varies the time.on of the heating. current, whereas/adjustment of variable bias. discharging resistor 62, with thyratron 68, and like previously described- -variable resistance 35 and its thyratron 31, is a-load sensitive me'ans and varies the time ofi. Resistor 35a gives protection for excessively high current pulses through the device being outgassed, and voltage divider 5,! protects against voltage increases across said device. Such voltage across the device on exhaust increases when said device loses emission, especially when the voltage regulation of the system is poor.

We claim:

1. An electrical system comprising a rectifier having an input connection for alternating current to be rectified and having grid-controlled electronic devices for full-wave rectification of said alternating current and having output connections for the rectified current, means for pulsing the rectified current, said means automatically and repeatedly applying a negative bias to said grid controlled electronic devices thereby repeatedly interrupting and re-establishing current output therefrom in a pulsed cycle, and a load-sensitive means comprising mechanism rendered conductive in consequence of increase of current drawn by the load, said load-sensitive means being coupled with said electronic devices and connected supplementally to said pulsing means for also applying a negative bias to said grid-controlled electronic devices and thereby interrupting the pulsed output from the rectifier.

2. An electrical system comprising a. rectifier having an input connection for alternating current to be rectified and having grid-controlled electronic devices for full-wave rectification of said alternating current and having output connections for the rectified current, means for pulsing the rectified current, said means automatically and repeatedly applying a negative bias to said grid controlled electronic devices thereby repeatedly interrupting and re-establishing current output therefrom in' a pulsed cycle, and a load-sensitive means comprising a third electronic control device rendered increasingly conductive with increase in demand on the output and current drawn by the load, the said third electronic control device being coupled with the first-mentioned electronic devices and connected supplementally to said pulsing means for also applying a negative bias to said first-mentioned electronic devices and thereby interrupting the pulsed output from the rectifier.

3. An electrical system comprising a rectifier having an input connection for alternating current to be rectified and having grid-controlled electronic devices for full-wave rectification of said alternating current and having output connections for the rectified current, means ior pulsing the rectified current, said means automatically and repeatedly applying a negative bias to said grid controlled electronic devices thereby repeatedly interrupting and re-establishing current output therefrom in a pulsed cycle, and

.mentally to said pulsing means for also applying a negative bias to said first-mentioned electronic devices and thereby interrupting the pulsed output from the rectifier.

HAMPTON J. DAILEY. JOHN J. BORZIN.

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

UNITED STATES PATENTS Number Name Date 1,649,016 Buckley Nov. 15, 1927 1,859,082 Fitzgerald et al May 7, 1932 2,039,043 Westendorp Apr. 28, 1936 2,095,742 Haller Oct. 12,1937 2,098,051 Lord Nov. 2, 1937 2,113,220 Power Apr. 5, 1938 2,134,710 Eitel Nov. 1, 1938 2,276,994 Milinowski Mar. 17, 1942 2,295,585 Lindquist Sept. 15, 1942 2,303,453 Gulliksen Dec. 1, 1942 2,306,378 Brown Dec. 29, 1942 2,307,620 Clark Jan. 5, 1943 2,323,440 Baird July 6, 1943 2,403,745 Norton July 9, 1946

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