US2412542A - Deflection circuits - Google Patents

Description

Dec. 10, 1946. chSMlTH 2,412,542

DEFLECTI ON CIRCUITS Filed May 25, 1944 INVENTOR.

nyyrffgm ATTORNEY Patented Dec. 10, 1946 UNITED STATES PATENT OFFICE DEFLECTION CIRCUITS Lester C. Smith, Westmont, N. J., assignor to Radio Corporation of America, a corporation of Delaware Claims. 1

This invention relates to an improvement in cathode ray beam deflection generators for use in oscilloscopic or other related apparatus.

As is well known to those skilled in the art, a cathode ray oscilloscope includes, in general, a circuit arrangement for causing the cathode ray beam that is generated in a cathode ray tube to be repeatedly deflected across the viewing screen of the cathode ray tube in a horizontal direction, while the transient or voltage variation to be observed is generally applied, after appropriate amplification, to the vertical deflecting plates of the cathode ray tube to cause the beam to be deflected in a vertical direction across the screen of the cathode ray tube. The horizontal deflection circuit is generally so constructed as to permit the deflection rate to be varied within very wide limits in order that the rate at which the cathode ray beam is deflected horizontally (generally in a linear manner) may be varied to permit convenient inspection of the trace regardless of the rate of variation of the voltage variations under observation.

In normal use of the cathode ray oscilloscope, the horizontal deflections of the cathode ray beams are continued at a predetermined rate, and if the voltage variations under observation reoccur at a predetermined rate, a proper choice of the recurrence rate of the horizontal deflection of the cathode ray beam will cause a substantially stationary trace or image to appear on the screen of the cathode ray tube. 7

There are instances, however, when the voltage variation or phenomenon under observation is not regularly recurrent, and under these circumstances it is not possible to relate the horizontal deflection rate to the occurrence frequency of the voltage variations under observation, with the result that a substantially stationary image cannot be produced on the viewing screen of the cathode ray tube.

Under conditions where the transient voltage variation to be observed is not regularly recurrent, cathode ray Oscilloscopes have been used in which a so-called single sweep operation is possible, and under these circumstances the cathode ray beam is generally biased to remain normally stationary, with circuit arrangements such that when a transient condition is impressed upon the apparatus to cause vertical deflections of the cathode ray beam, a simultaneous single sweep or single horizontal deflection of the cathode ray beam is brought about.

When the cathode ray beam is normally biased in a stationary condition at the right hand side of 2 the viewing screen, the cathode ray beam must first be quickly deflected to the left side of the screen before the sweep or relatively slower deflection can take place from the left side of the screen to the right in the usual manner. This interval in returning the cathode ray beam to the left side of the screen prior to its deflection at a predetermined rate occupies some period of time, and accordingly it is possible that a portion of the voltage variations to be observed will be lost during this return time interval. Should the transient condition prevail for a relatively short space of time, an appreciable portion of the voltage variations to be observed may be entirely lost even though the deflection rate may be increased to a relatively high speed.

Furthermore, in such devices as have heretofore been used, the circuit arrangement for causing the single sweep action has not been wholly satisfactory since in many cases a rather intense triggering potential is required to cause operation of the single sweep mechanism. This initial intense impulse is in many instances not available, since it is not uncommon for a transient condition to commence at relatively low amplitude, and under such circumstances the single sweep circuit arrangement would not respond until the transient condition has persisted for an appreciable portion of its interval.

Also, in other single sweep circuits, the selection of sweep rates is ordinarily adjustable only in fixed steps or over a relatively narrow range and the signal under observation must be recurrent within certain fixed time limits.

In order to overcome these difficulties, the present invention provides a single sweep circuit arrangement whereby the cathode ray beam is normally biased in a stationary position at the left side of the screen so that upon the occurrence of a transient condition or a voltage variation to be observed, the cathode ray beam is in immediate condition to start its useful deflection from the left to the right side of the viewing screen. Furthermore, in accordance with the present invention and by reason of the particular single sweep circuit arrangement provided therein, the single sweep operation may be initiated on a relatively low intensity voltage variation in order that virtually all of the transient condition may be effective in producing an observable signal trace on the viewing screen of the cathode ray tube. In addition to these provisions, the single sweep circuit arrangement also provides means whereby the rate of sweep may be continuously varied within wide limits to cause the cathode ray beam to traverse the screen at any desired rate, and furthermore, by means of the present circuit arrangements the transient to be observed may reoccur as rapidly as 20,000 or more times per secnd or at any slower rate, even to a single isolated instance. Regardless of the duration or occurrence rate of the transient the circuit arrangernent can be adjusted to produce a single deflection of the cathode ray beam for each individual transient and by controlling the rate of deflection the trace produced by the transient can be caused to occupy a substantial portion of the useful area of the observation screen.

One of the purposes of the present invention resides, therefore, in the provision of a new and improved single sweep circuit arrangement for use in connection with cathode ray oscilloscope apparatus.

Another purpose of the present invention resides in the provision of a single sweep circuit arrangement for a cathode ray oscilloscope in which the cathode ray beam is normally biased in its returned position, the return deflection of the cathode ray beam taking place immediately following each single sweep deflection rather than immediately prior to each single sweep deflection.

Still another purpose of the present invention resides in the provision of means whereby the single sweep deflection circuit may be caused to respond to relatively low intensity voltage vari ations derived from the applied transient to be observed.

Still a further purpose of the present invention resides in the provision of a single sweep deflection circuit for use with a cathode ray oscilloscope in which the rate of deflection during each deflection cycle may be varied within very wide limits.

Another purpose of the present invention resides in the provision of a single sweep deflection circuit for use in an oscilloscope in which proper single sweep operation will result regardless ofthe repetition frequency of the transient, or even in the absence of any repetition.

Still other purposes and advantages of the present invention will become more apparent to those skilled in the art from the following detailed description of the invention, particularly when considered in connection with the drawing, wherein the single figure represents a preferred form of the present invention.

Referring now to the drawing, the single sweep deflection circuit includes two electron discharge tubes l8 and i2, each of which includes at least a cathode, a control electrode and an anode.

The cathode it of tube i0 is connected to ground by way of cathode resistance I6, in series with which may be connected a small inductance H3. The control electrode 20 of tube I0 is connected to input terminal 22 by way of coupling condenser 24 and relatively small resistance 26. The condenser 24 and resistance 26 are connected in series, and the junction of these elements is connected to ground by Way of grid resistor 28. The anode 53 of tube ill is connected to positive terminal 32 (to which anode supply voltage is applied) by way of load resistance 34.

For coupling tube ID to tube I2, a plurality of selectable coupling condensers 36, 31, and 38 are employed, and one terminal of each of these condensers is connected to the anode 30 of tube It]. The other terminal of each of these condensers is connected to a selector switch 40 in order that one of the condensers may be individually selected and included in the circuit. A movable arm or" the selector switch 48 is connected to the control electrode 32 of tube 12 by way of small resistance 34. A grid resistance is connected between the cathode l6 of tube Ill and the junction of selector switch 48 and resistance 44. This grid resistance includes preferably a fixed resistance element 46 and a variable resistance elernent 48. The cathode 50 of tube I2 is shown connected to the cathode Hi of tube it by way of resistance 52, although this resistance is not essential in all instances. This resistance 52 is small as compared with the cathode resistance IG, and if included in the circuit provides some automatic biasing of tube l2 relative to the biasing of the cathode M of tube In. The cathode resistance i6 is naturaly common to both tubes.

A plurality of selectable sweep condensers 54, 55 and 59 are included between an anode 58 of tube E2 and ground. One terminal of each of the condensers is connected to the anode 58 whereas the other terminal of a selected one of the condensers may be connected to ground by way of selector switch til. For proper operation of the system, the series of condensers 54, 55 and 58 is preferably about ten times the capacity of the series of condensers 36, 3?, and 38, and the two selector switches 40 and 69 are preferably ganged together for simultaneous operation.

The anode 53 of tube i2 is connected to positive terminal 3?. by Way of fixed resistance 62 and variable resistance 64. The variable resistance as included in the anode circuit of tube l3. and the variable resistance 48 connected in the grid circuit of tube l2 are preferably ganged together in order that their values may be simultaneously controlled. Variation in the size of resistance 64 affects the charging rate of the selected condenser 56, 55 or 56 and accordingly provides a Vernier or fine adjustment for determining the sweep rate and length of sweep, while simultaneous adjustment of resistance 48 changes duration of chargin cycle and thereby determines total amount of charge of potential of anode 58. The coarse adjustment is, of course, determined by the particular pair of condensers selected by the selector switches ti! and 53.

The voltage variations appearing across the selected condenser 54, 55 or 56 provide the. desired sweep potential variations, and accordingly the output may be derived from terminals 65 connected between ground and the anode 58 of tube l2.

In general, the deflection voltage variations are produced by a charging of the condenser selected by selector switch 553 from positive terminal 32 over resistances 54 and 62. As long as the condensers are not permitted to charge to the full applied position potential, a substantially linear charge condition or voltage variation may be produced at the anode 53 of tube [2. When the charge has reached a predetermined proportion, the tube i2 is permitted to conduct, which results in a substantially instantaneous discharge of the selected condenser through tube l2. During this discharge interval, current flows through tube I2 and, accordingly, through cathode resistances 16 and 52. The voltage drop produccd across resistance i6 therefore drives the cathode of tube ill in a positive direction, resulting in an increase in the bias of tube i8 which causes this tube to become non-conductive. For single sweep operation, this condition of conduction through tube i2 should persist, and the substantiallynon-conduction condition of tube Ill should also persist.

When it is desired to permit a charge to accumulate on one of the selected condensers 54, 55 or 56, and accordingly, to cause a. deflection of the cathode ray beam, a positive triggering impulse is applied to the control electrode 20 of tube I which renders tube I0 conductive and the potential at the anode of tube I6 is, therefore, driven in a negative direction. This negative impulse in then applied by Way of one of the selected condensers 36, 31 or 33 to the control electrode 42 of tube I2 to render tube I2 non-conductive. During its non-conductive condition, the selected condenser 54, 55 or 56 is permitted to charge through resistances 62 and 64 and, accordingly a sweep deflection potential variation is developed. Immediately following the sweep deflection tube I2 discharges the particular charged condenser and renders tube Ill non-conducting, or substantially so, thus preparing the circuit for the next operation cycle.

In order that this desired cycle of operation may be assured and in order that the circuit may be responsive to relatively low intensity triggering potentials applied to the control electrode 20 of tube ID, the circuit includes, in addition to the elements above described, diodes or unidirectional conducting devices 68 and I0. Each of these diodes includes at least a cathode and an anode.

For maintaining proper operating potential on the electrodes of the diodes, two potentiometers I2 and I4 may be connected in series between positive terminal 32 and ground or the negative anode supply voltage. The anode I6 of nected to the anode 30 of tube III, while the oathode I8 element is connected to the movable contact of the potentiometer I2. The cathode 86 of diode I0 is connected to the anode 58 of tube I2, while .the anode 82 of diode I0 is connected to the movable contact of potentiometer I4. The diode I0 operates primarily to assure a continued conducting condition of tube I2 to maintain tube I0 substantially non-conducting in the absence of any triggering or synchronizing impulses, and to limit the amplitude of excursion of anode 56 in the negative direction (less positive). Furthermore, the diode 68 causes the efiective gain of tube III to be reduced to a very low value during its periods of substantial inactivity. With the diodes 68 and I3 included in the circuit, the operation of the single sweep arrangement herein described will now be discussed.

In describing the operation of the system it will be assumed that the selected one of the condensers 54, 55 or 56 has been discharged by conduction through tube I2, and that the tube is maintained in a conducting condition by reason of the presence of the diode H3. The resistance values of the resistance 62 and the potentiometer 64 is fairly high and, as a result, if the diode It! were not included in the circuit, the potential of the anode of tube I2 would drop to a, relatively low amount determined primarily by the impedance of the tube I2. It will be noticed, however, that the anode of the diode I6 is connected to a movable contact along the potentiometer 14 which maintains the anode 82 of the diode I0 at a predetermined and adjustable positive potential relative to ground.

As soon as the anode 58 of tube l2 drops below this positive potential, the cathode 80 of the diode I6 then becomes negative with respect to the anode 62 and current is permitted to flow through the diode 10. This, in effect, forms a parallel diode 68 is contial determined by the setting of the movable contact along the potentiometer I4. Tube I2 will, therefore, continue to conduct and the selected condenser 54, 55 or 56 will be maintained in a discharged condition.

Furthermore, since the ungrounded terminal of the selected condenser is connected to the anode 58 of tube I2, an adjustment of the movable contact along potentiometer I4 will determine the potential to which the particular selected condenser is discharged. While tube I2 remains in this conducting condition, tube In is substantially non-conducting, and since the diode 68 is, in effect, connected in parallel with the load impedance 34 of tube N3, the gain of tube I0 is reduced to a very low value. It will be observed that the anode 16 of diode 68 is connected to the anode 3B of tube I0, whereas the cathode I8 of diode 68 is connected to a movable point along potentiometer I2.

When a positive triggering impulse is applied to terminal 22, tube I0 is rendered momentarily conducting since the bias on the tube is reduced, and this conducting condition causes the potential at the anode 30 of tube I0 to change in a negative direction which removes the effect of the diode 68 and subsequently causes a negative impulse to be applied by way of a selected coupling condenser 36, 31 or 38 to the control electrode 42 of tube 12. This negative impulse then increases the bias on tube I2, decreasing cathode current of tube I2, reducing voltage drop across resistor I6, which decreases bias on tube I0. This increases current through tube I0, which causes further change in potential of anode 36 in a nega- .tive direction, with the result that tube I2 is rendered non-conducting, and the selected condenser 54, or 56 is permitted to charge through resistances 62 and 64.

In the absence of any circuit elements, the selected condenser would naturally charge to the full potential applied to terminal 32 in the length of time determined by the time constant of the circuit, but considerably before any such charge condition has been reached, tube I2 is again rendered conductive to discharge the selected condenser. As is well known tothose skilled in the art, the charging of a condenser through a resistance is approximately linear for a time interval small compared to l/RC, and for producing linear deflections of a cathode ray it is desirable to not permit the condenser to operate appreciably beyond the substantially linear portion of its charge curve. The length of time that the selected condenser 54, 55 or 56 is permitted to charge is then determined by the value of resistances 46 and 68, the latter of which is made adjustable.

During the charge of the selected condenser 54, 55 or 56, the control electrode 42 of tube I2, which was driven in a negative direction (beyond cut-01f) by the impulse from tube In, gradually changes its potential in a postive direction by reason of a discharge of the selected condenser 3'6, 31 or 38 through resistances 46 and 48 thereby reducing the bias on tube I2. After the control electrode potential of tube I2 has changed in a positive directionby a predetermined amount, the tube I2 is again rendered conductive and a regenerative cycle occurs the reverse of that described above, which culminates in the control electrode Q2 of tube l2 being driven to zero bias, or slightly positive. Tube l2 then begins to discharge the selected condenser 56, 55 or 56. As stated above, the length of time that grid 42 is negative beyond cut-off is determined by the time constant of resistances 4E and 68' together with the particular selected condenser 38, 31 or 38.

After tube I2 has been rendered conductive, the selected condenser 5 55 or 53 is then discharged and in the absence of a further triggering or synchronizing impulse, tube i2 remains conductive and the selected condenser remains discharged. The circuit remains in this quiescent condition until a further positive triggering impulse is applied to tube iii, and upon such an application the cycle is again repeated.

Since the selected condenser 5:1, 55 or 55 is only permitted to charge to a small percent-age of the potential applied to terminal 32, and since the particular condenser is discharged substantially instantaneously through tube 112, a sawtooth shaped voltage variation may be derived between the anode of tube l2 and a point of fixed potential. Accordingly, potential variations of sawtooth wave form may be obtained from terminal 65. The slope of the produced sawtooth wave, as well as its time duration, may be determined by proper selection of the condensers by means of the selector switches 26 and 60 which are preferably ganged together, and a Vernier or fine adjustment of the slope and time duration may be accomplished by a variation in the values of the resistances 48 and 64, the controls for these values being also preferably ganged together. The signal output intensity from terminals 56 and the linearity of wave form remain substantially constant regardless of the chosen sweep rate.

By means of the circuit arrangement and the controls associated therewith, it is therefore possible to produce potential variations suitable for deflecting a cathode ray beam in a linear manner, the rate of sweep being controlled within wide limits so that the cathode ray beam may be caused to traverse a screen relatively slowly or very rapidly, the traversal being maintained substantially linear regardless of the particular rate.

Since the circuit arrangement described is not periodic in operation, but is instead aperiodic, these voltage variations of sawtooth wave form are not regularly recurrent but are produced only as a result of the application of a positive triggering or synchronizing impulse to the control electrode o1" tube I ii. The circuit shown can, however, conveniently be converted to a periodic sweep generator by merely changing the value of the resistance I 6. Under such conditions the diodes 88 and 10 are not necessary.

Due tothe critical biasing of tube iii and the presence of diode 68, a very low intensity triggering or synchronizing impulse is eifective to cause operation of the circuit and thereby to produce a voltage variation for deflecting the cathode ray beam in order that an oscillographic trace of a transient condition may be produced.

From the above description it may be seen, therefore, that the present invention differs from usual single sweep deflection arrangements in that a voltage variation for deflection is produced such that the cathode ray beam of the tube is normally biased in a position at the starting side (generally the left hand side) of the viewing screen. Under these circumstances, the beam is immediately in condition to begin its useful deflection across the screen of the viewing tube as soon as a triggering impulse is applied. In the usual single sweep deflection circuit, the application of a synchronizing or triggering impulse first causes the usual return of the cathode ray beam which is immediately followed by the useful defiection stroke. In the present invention, however, the application of a triggering or synchronizing impulse first causes the useful traversal or deflection of the cathode ray beam which is immediately followed by the return deflection stroke.

The application of a triggering or synchronizing impulse in the present invention, therefore, does not first result in a discharge of the sweep condenser, as is the usual case, but instead immediately results in the charging of the sweep condenser, the charged condition being immediately followed by the discharge cycle, at which point the system remains inactive until a further triggering or synchronizing impulse is applied. For this reason there is no time delay in the immediate presentation of the oscilloscope trace, and since the deflection circuit described herein will respond to very low intensity triggering impulses, it is possible to produce on the screen of the cathode ray oscilloscope an entire transient condition even though the initial portion of the transient condition is of low amplitude. Furthermore, should the transient condition persist for a very short length of time, the entire transient condition is still presented on the screen of the oscilloscope by reason of the fact that no portion of the time occupied by the transient condition is consumed in the return deflection of the cathode ray beam.

Various alterations and modifications may be made in the present invention without departing from the spirit and scope thereof, and it is desired that any and all such alterations and modifications be considered within the purview of the present invention, except as limited by the hereinafter appended claims.

Having now described my invention, what I claim is:

1. A circuit arrangement for producing single sweep deflection voltage variations for a cathode ray oscilloscope in response to individual triggering impulses comprising a first and second electron discharge tube each having a cathode, a control electrode and an anode, means including a common impedance element for connecting the cathodes of the tubes to a point of fixed potential, and means for applying the triggering impulses to the control electrode of the first electron discharge tube, means including a load impedance for maintaining the anode of the first electron discharge tube positive with respect to its associated cathode so that potential variations are present at the anode of said tube in response to the applied triggering impulses, means for coupling the anode of said first electron discharge tube to the control electrode of said second electron discharge tube, means including an adjustable resistance for maintaining the anode of the second electron discharge tube positive with respect to its associated cathode, a condenser connected between the anode of the second electron discharge tube and a point of fixed potential so that the condenser may be charged through the resistance associated with the second electron discharge tube and so that the condenser may be discharged by said second electron discharge tube in response to potential variations applied to the control electrode of said tube from said first electron discharge tube, a first diode including a cathode and an anode, means for connecting the anode of said first diode to the anode of said first electron discharge device, and means for applying a predetermined positive potential to the cathode of said first diode so that said first electron discharge tube may be maintained in a substantially non-conducting condition in the absence of a positive triggering impulse, a second diode including a cathode and an anode, means for connecting the cathode to the anode of said second electron discharge tube, and means for applying a predetermined positive potential to the anode of said second diode in order to maintain a conductive condition of said second electron discharge tube in the absence of applied potential variations whereby single sweep potential variations may be produced at the anode of said second electron discharge tube in response to the application of a, triggering impulse to the first electron discharge tube.

2. A circuit arrangement for producing single sweep deflection voltage variations for a cathode ray oscilloscope in response to individual triggering impulses comprising a first and second electron discharge tube each having a cathode, a control electrode and an anode, means including a common impedance element for connecting the cathodes of the tubes to a point of fixed potential, means for applying the triggering impulses to the control electrode of the first electron discharge tube, means for maintaining the anode of the first electron discharge tube positive with respect to its associated cathode so that potential variations are present at the anode of said tube in response to the applied triggering impulses, means for applying the produced potential variations to the control electrode of said second electron discharge tube', means including a resistance for maintaining the anode of the second electron discharge tube positive with respect to its associated cathode, an electron storage element connected between the anode of the second electron discharge tube and a point of fixed potential so that the electron storage element may be charged through the resistance associated with the second electron discharge tube and discharged by said second electron discharge tube in response to potential variations applied thereto, a first unilateral conducting device including a cathode and an anode, means for connecting the anode of said first unilateral conducting device to the anode of said first electron discharge device, and means for applying a predetermined positive potential to the cathode of said first unilateral conducting device, a second unilateral conducting device including a cathode and an anode, means for connecting the cathode to the anode of said electron discharge tube, and means for applying a predetermined positive potential to the anode of said second unilateral conducting device whereby single sweep potential variations may be produced at the anode of said second electron discharge tube in response to the application of a triggering impulse to the first electron discharge tube.

3. A circuit arrangement for producing single sweep deflection voltage variations for a cathode ray oscilloscope in response to individual triggering impulses comprising a first and second electron discharge tube each having a cathode, a control electrode and an anode, means including a common impedance element for connecting the cathodes of the tubes to a point of fixed potential, means for applying the triggering impulses to the control electrode of the first electron discharge tube, means including a load impedance for maintaining the anode of the first electron discharge tube positive with respect to its associated cathode so that potential variations are present at the anode of said tube in response to the applied triggering impulses, means for applying the produced potential variations to the control electrode of said second electron discharge tube, means including a load resistance for maintaining the anode of the second electron discharge tube positive with respect to its associated cathode, an electron storage element connected between the anode and the second electron discharge tube and a point of fixed potential 50 that the electron storage element may be charged through the load resistance associated with the second electron discharge tube and discharged by said second electron discharge tube in response to potential variations applied thereto, a first unilateral conducting device effectively connected in parallel with the said load impedance so that said first electron discharge tube may be maintained in a substantially non-conducting condition in the absence of a positive triggering impulse, a second unilateral conducting device efiectively connected in parallel with the said load resistance in order to maintain conducting condition of said second electron discharge tube in the absence of the potential variations produced at the first electron discharge tube whereby single sweep potential variations may be produced at the anode of said second electron discharge tube in response to the application of a triggering impulse to the first electron discharge tube.

4. A single sweep deflection generator including a first and second electron discharge tube each including a cathode, a control electrode and an anode, means including a common cathode impedance for connecting the cathodes of the tubes to a point of fixed potential, means including a load impedance for maintaining the anode of the first electron discharge tube positive with respect to its cathode, means for applying triggering potentials extending in a positive direction to the control electrode of the first electron discharge tube to produce corresponding potential variations extending in a negative direction at the anode of said tube, means to assure a substantially non-conducting condition of the first electron discharge tube in the absence of a triggering impulse comprising a diode having an anode and a cathode, means for effectively connecting the diode in parallel with the load impedance of the first electron discharge tube, means including an adjustable resistance for maintaining the anode of the second discharge tube positive with respect to its cathode, a condenser connected between the anode of said second tube and a point of fixed potential, so that the condenser may be charged through said adjustable resistance and discharged by said second tube in response to the application of the voltage variations from said first electron discharge tube to the control electrode of saidsecond electron discharge tube, and means to assure a conducting condition at said; second electron discharge tube in the absence of an applied potential variation to the control electrode of saidtube comprising a diode having a cathode and an anode, and means for connecting the diode effectively in parallel with the adjustable resistance whereby the condenser will be charged through said resistance to a predetermined potential level and immediately be discharged by said second electron discharge tube in response to the application of a single triggering impulse 1 l to the control electrode of the first electron discharge tube to produce single sweep potential variations at the anode of said second tube.

5. A single sweep deflection generator including a first and second electron discharge tube each including a cathode, a control electrode and an anode, means including a common cathode impedance for maintaining the cathode of the tubes at substantially the same potential, means including av load impedance for maintaining the anode of the first electron discharge tube positive with respect to its cathode, means for applying triggering potentials extending in a predetermined direction to the control electrode of the first electron discharge tube to produce potential variations at the anode of said tube, means to normally assure a substantially non-conducting condition of the first electron discharge tube comprising a diode, means for effectively connecting the diode in parallel with the load impedance of the first electron discharge tube, means including a resistance for maintaining the anode of the second discharge tube positive with respect to its cathode, a condenser connected between the anode of said second tube and a point of fixed potential so that the condenser may be charged through said resistance and discharged by said second tube in response to the application of the produced voltage variations to the control electrode of said second electron discharge tube, and means to normally assure a conducting condition at said second electron discharge tube comprising a diode, and means for connecting the diode effectively in parallel with said resistance whereby the condenser will be gradually charged to a predetermined potential level and immediately quickly discharged by said second electron discharge tube in response to the application of a single triggering impulse to the control electrode of the first electron discharge tube to produce single sweep potential variations at the anode of said second tube.

6. A sin le sweep deflection generator including a first and second electron discharge tube each including a cathode, a control electrode and an anode, means includin a common cathode impedance for connecting the cathodes of the tubes to a point of fixed potential to maintain the cathodes at substantially the same potential means including a load impedance for maintaining the anode of the first electron discharge tube positive with respect to its cathode, means for applying a triggering potential to the control electrode of the first electron discharge tube to produce a corresponding potential variation at the anode of said tube, means including a resistance for maintaining the anode of the second discharge tube positive with respect to its cathode, a condenser connected between the anode of said second tube and a point of fixed potential, so that the condenser may be relatively slowly charged through said resistance and quickly discharged by said second tube in response to the application of the produced voltage variation to the control electrode of said second electron discharge tube, and means to assure aperiodic operation of the deflection generator and to normally maintain a conducting condition at said second electron discharge tube in the absence of an applied potential variation to the controlelectrode of said tube comprising a diode, and means for effectively connecting the diode in parallel with the resistance whereby the condenser will be charged to a predetermined potentiallevel and will be im- 12 mediately discharged by said second electron discharge tube in response to the application of a single triggering ilnpulse to the control electrode of the first electron discharge tube thereby to produce a single sweep potential variation at the anode of said second tube.

7. A single sweep deflection generator including a first and second electron discharge tube, each tube including a cathode, a control electrode and an anode, means for maintaining the cathodes at substantially the same potential including a common impedance for connecting the cathodes to a point of fixed potential, means for applying individual triggering impulses to the control electrode of the first electron discharge tube to produce potential variations at the anode of said tube, means for applying the produced potential variations to the control electrode of the second electron discharge tube, means including an adjustable resistance for maintaining the anode of the second electron discharge tube positive with respect to its associated cathode, a condenser connected between the anode of the second electron discharge tube and a point of fixed potential whereby the condenser may be relatively slowly charged through theadjustable resistance and quickly discharged by said second electron discharge tube, a. first and second unilateral con ductingdevice individually associated withthe anode circuit of the electron discharge tubes to assure a normally substantially non-conducting condition of the first electron discharge tube and a normally conducting condition of the second electron discharge tube so that upon the application of an individual triggering impulse to the control electrode of the first electron discharge tube the said condenser will be charged to a predetermined potential value and will be immediately discharged by said second electron discharge tube thereby assuring aperiodic operation of the circuit to produce single sweep potential variations at the anode of the second electron discharge tube in response to applied triggering impulses to the first electron discharge tube.

3. A single sweep deflection generator including a first and second electron discharge tube, each tube including a cathode, a control electrode and an anode, means for maintaining the cathodes of said tubes at substantially the same potential, means for applying individual and sporadic triggering impulses. to the control electrode of the first electron discharge tube to. produce potential variations at the anode of said tube, means for applying the produced potential variations to the control electrode of the second electron discharge tube, means including an adjustable impedance for maintaining the anode of the second electron discharge tube positive with respect to its associated cathode, a condenser connected between the anode of the second electron discharge tube and a. point of fixed potential whereby the, condenser may be relatively slowly charged through the adjustable impedance andsubstantially. instantaneously discharged by said second electron discharge tube, a first and second unilateral conducting device individually associated with the anode circuit of the electron discharge tubes to normally assure a substantially non-conducting condition of the first electron discharge tube and a normally conducting condition of the second electron discharge tube thereby assuring aperiodic operation of the deflection generator to produce a single sweep potential variation cycle at the anode of the second electron discharge tube a 3 in response to each applied triggering impulse to the first electron discharge tube.

9. A single sweep deflection generator including a first and second electron discharge tube, each tube including a cathode, a control electrode and an anode, means for maintaining the cathodes at substantially the same potential, means for applying a triggering impulse to the control electrode of the first electron discharge tube to produce a corresponding potential variation at the anode of said tube, means for applying the produced potential variation to the control electrode of the second electron discharge tube, means including an impedance for maintaining the anode of the second electron discharge tube positive with respect to its associated cathode, a condenser connected between the anode of the second electron discharge tube and a point of fixed potential whereby the condenser may be slowly charged through said impedance and quickly discharged by said second electron discharge tube, a unilateral conducting device effectivzely connected in parallel with said impedance to assure aperiodic operation and to normally maintain a conducting condition of the second electron discharge tube so that upon the application of a triggering impulse to the control electrode of the first electron dischargetube the condenser associated with said second electron discharge tube will be charged to a predetermined potential level and will immediately be discharged by said second electron discharge tube to produce a single sweep deflection cycle across said condenser.

10. A single sweep deflection generator including a pair of electron discharge tubes each including an anode, a control electrode and a cathode, means for applying triggering impulses eX- tending in a predetermined potential direction to the control electrode of one of said tubes to produce a voltage variation extending in a predetermined direction, means to maintain the oathodes of the two tubes at substantially the same potential, means to apply the produced voltage variations to the control electrode of the other electron discharge tube, a condenser connected between the anode of the said other electron discharge tube and a point of fixed potential, an adjustable charging resistance and source of positive potential associated with said condenser so that the condenser may be gradually charged through said resistance and quickly discharged by said other electron discharge tube in response to an applied voltage variation, means including a unilateral conducting device effectively connected in parallel with the anode circuit of each electron discharge tube to assure aperiodic operation of the deflection generator so that the condenser is charged and immediately discharged upon the application of each individual triggering impulse.

LESTER C. SMITH.

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