US2396439A

US2396439A - Electron tube circuits

Info

Publication number: US2396439A
Application number: US434805A
Authority: US
Inventors: Schlesinger Kurt
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1942-03-16
Filing date: 1942-03-16
Publication date: 1946-03-12
Anticipated expiration: 1963-03-12

Description

March 12, 1946. K. SCHLESINGER 2,396,439

ELECTRON TUBE CIRCUITS Filed March 16, 1942 M4 M6 -31--- we ,2?

' !NVENT( )R. mrwdwerger ATTOR Y Patented Mar. 12, 1946 ELECTRON TUBE CIRCUITS Kurt Schlesinger, West Lafayette, Ind., asslgnor to Radio Corporation of America, a corporation of Delaware Application March 16, 1942, Serial No. 434,805

11 claims.

The present invention relates generally to devices for developing linear voltage waves and is particularly applicable for developing the energy for deflecting an electron beam generated within a cathode ray tube.

Such circuit arrangements are directly and particularly applicable to television receivers and to other forms of electronic circuits wherein provision is to be made for causing an electron beam to be deflected relatively slowly and strictly linearly in one direction of its traverse and to be returned very rapidly to a starting point after reaching a predetermined point in its deflection. In one of the best-known forms of such arrangements as applied to a cathode ray tube device for television the cathode ray beam is deflected across a target in each of two mutually perpendicular directions, of which the movements in the two directions of deflection are harmonically related and in which each initial portion of the movement takes place much slower than the latter portion. Also the invention is particularly applicable to use with oscillograph apparatus where it is desired that wave trace investigations be made and where it is particularly desired that the traced phenomena shall be maintained substantially stationary during the investigation.

In the prior art circuits are known by which it is possible to produce linear voltage waves of saw-tooth form which may serve as the energy for the driving stage for deflection in connection with electrostatic or electromagnetic deflection of a cathode ray beam developed within a cathode ray tube. In such conventional deflection circuits three stages are usually provided, of which the first consists of an impulse generator connected as a blocking oscillator tube of well-known form and illustrated, for example, by the Tolson Reissue Patent a t-20,338. The second stage consists, for instance, of a discharge tube which derives its positive control electrode impulse from the blocking oscillator. The final stage usually consists oi the amplifier.

One of the objects of the present invention is to accomplish results commensurate with the circuits of the prior art and at the same time to provide simplifications in the circuit design and arrangement by which it will be possible to reduce the number of tubes required to accomplish the desired results. In one of the preferred forms of the invention the actions of the first two circuit elements above named, namely the blockin; oscillator tube and the discharge tube, are combined into a single instrumentality.

a circuit arrangement wherein it is possible to generate and deliver directly to an output circuit energy or saw-tooth wave form and without addition of further coupling elements which could introduce distortion, and especially distortion at the lower frequencies.

A further object of the invention is to provide further simplification and to arrange at the same time so that the blocking stage develops sufiicient power to deliver a sufficient charge to an oscilfor all frequencies at which the saw-tooth wave energy is developed.

Still a further object of the invention is that of developing a saw-tooth wave oscillator and generator system in which the saw-tooth frequency is made independent of fluctuations in the voltage supplied to the system.

Other objects are to provide a system by which the amplitude of the output energy can be regulated readily merely by varying suitable parameters of the system without otherwise affecting thereliability of the sytsem.

Still another object of the invention is to pro= vide a system in which amplification oi the output energy from the oscillator and discharge tube combination mayreadily be had without introducing any new distortion into the system.

Still other objects of the invention are to provide a system by which saw-tooth wave energy may be developed with a minimum number of tubes and component parts by which the costs of such systems may be reduced and in which the efilciency oi operation may be increased.

Other objects and advantages of the invention will become apparent from considering the following specification and the claims hereinafter appended in connection with the accompanying drawing, in which:

Figure 1 is a simplified diagram of one form oi circuit; and,

A further object of the invention is to provide as Figure 2 is a modification oi the arrangement of Figure 1 providing for' obtaining a wide range of sweep or deflection frequencies,

Referring now to the drawing for a further understanding of the invention, in the arrangement of Figure 1 there is disclosed a form of deflection circuit in which an inductively coupled triode oscillator is used to produce a sawtooth voltage wave directly. In the arrangement, there is a triode tube I comprising the anode II, the control electrode II and the cathode II. A suitable source of voltage (not shown) is provided with its positive terminal connected to the terminal I2 which, in turn, supplies positive voltage to the anode II of the tube I0 by way of the transformer winding I3. The cathode I1 is connected to ground I9 through the cathode resistor 2|. In a path parallel to the path between the transformer winding I 3 and ground I9 there is provided a variable resistor 52 which is connected to the terminal I2, whereat positive voltage appears, and, in series with the resistor 52 and ground I9, there is connected a condenser 25 which is arranged to be charged to a maximum potential er by way of the resistor 52. Feedback between the plate or anode II and the control electrode II of tube I0 is provided by way of the second transformer winding I8, which connects at one terminal thereof to the tube control electrode I4 and, at the other terminal thereof, to the junction of the resistor 52 and the condenser 25. In this arrangement, a synchronizing impulse of any desired frequency, depending upon the operating parameters, is applied in a negative sense at the terminal so as to be fed into the cathode circuit of the tube I0 by way of the cathode resistor through a connection made available at the point 22, for instance. The curve adjacent Figure 1 indicates, generally, the voltage across the condenser. In this arrangement it will be seen that positive plate voltage applied to the tube at the terminal I2 co-operates in the charge of the condenser through the charging resistor 52, which may be made variable, as indicated. In this way it is evident that the voltage across condenser 25 is always negative and its highest peaks only in a positive direction are touching the zero grid line (as shown) whereby tube In is unblocked and performs the flyback cycle, the negative amplitude of which is determined by the limiting resistor 2|.

In the arrangement of Figure 2 there is included an arrangement for providing a wide range of variancesof sweep frequencies which shall be stable and linear, as well as fixed amplitude for all ranges, and not subject to change with change.

in voltage over a wide range of frequencies. Referring now to the circuit of Figure 2 there is shown by the tube sections 'II and 12 two separate half sections of a double triode tube, for instance, a tube known in the art as the 6F8, which is illustrated in half sections for simplicity of diagram. In the tube section II there is provided the usual cathode I3, the control electrode I4 and the plate or anode I5. The cathode connects to ground III by way of a plurality of separate resistor elements I8, 11, I8, I9 and 80, of which the resistors I8 and I9 are respectively shunted by capacity elements 8I and 82. Synchronizing impulses are supplied to the tube from the terminal connection 83, by way of the condenser 84 and resistor 85, and the amplitude of the synchronizing impulse as it is applied is controlled by variation of the tapping point 80 on the resistor 80. Connections are made from the point 81 adjacent the cathode to a terminal 88 of a switching instrumentality. At the Junction point 89 between

resistors

16 and 11 there is a connection made 'to a second terminal point 00 of the switching instrumentality. Also from junction point 8| of the resistors 11 and I8 and one terminal of the condenser 8|, a connection is made to a further terminal 92 of the same switching instrumentality. From the junction point 03 of the resistor I8 and I9, as well as the lower side of condenser 8|, and the upper terminal of condenser 82 a connection is made to the terminal point 84 of the same switching instrumentality, and likewise to the junction point 95 of resistors I9 and 80 and the lower side of condenser 82 a connection is made to the last tapping point 96 on the switching instrumentality. The switch is provided with the switch arm 01 having one terminal thereof connected to the tapping point 80 and also to ground at I8 through the resistor 80. This switch is in uni-control arrangement with a second switch arm later to be described. The anode or plate member II of the tube section II is connected by way of the transformer winding IM to a terminal I02 to which anode voltage is applied to both halves of the tubes II, I2. The control electrode I4 is connected by way of the transformer winding Ill and the resistors I04 and I05 to the same terminal point I02. The control electrode II also connects through the transformer winding I03 and the potentiometer I 06 to ground at I8 and to the upper side of the various condenser elements I01, I08, I00, H0 and III, later to be described, Adjustment of the tapping point II2 on the potentiometer is made as desired through the resistor H3. The control electrode III of the tube section I2 connects to the Junction point II5 intermediate the resistors I04 and I05. Likewise plate or anode voltage is supplied from the terminal I02 through the resistor II8 to the anode or plate element I II of the tube section I2, and output energy from the tube may be derived from the terminal I I8, as indicated.

The cathode II9 of the tube section I2 is connected through the bias resistor I 20 shunted by the condenser I2I to ground at I8. As wa above noted, the upper terminals ofall of the condensers I01 through Ill, inclusive, connect to the control electrode ll of the tube section II. The lower terminals of these condensers connect respectively with the terminal points I23, I24, I20, I26 and I2! so that they may be individually connected to ground at I9 by way of the switch arm I28. The switch arms 91 and I28 are unicontrolled as conventionally shown by the connections I29 between the two witch arms.

It is, of course, to be understood that various values of condenser and resistor elements are capable of being used, and it is accordingly apparent that wide variation may be made for the desired frequency range. Likewise the type of tube shown may be varied. For the purpose of indicating a suitable range of frequency with respect to condenser and resistor elements, the following schedule is given as illustrated:

For any change in the type of timing circuit a corresponding change in the over-all resistor of the grid cathode particularly should be provided. Thus it happens that the tube delivers a reduced number of ampere seconds to a reduced capacity, resulting in obtaining substantially the same amplitude of the output for all ranges of frequency. The variation of the leak resistor 3 does not ailect the amplitude when once the system is adjusted. As shown by the diagram of Figure 2 it will be seen that direct coupling has been introduced between the tube section II and the succeeding amplifier section 12, At this point it might be remembered that, while the tube sections H and 12 are shown as halves of the same tube, it is, of course, apparent that two completely separate tubes may be used where desired. It is apparent also that if the oscillations take place in the negative portion of the grid bias the point i I along the leakage resistors I04 and "I5 may readily be determined so as to make the connection for the next succeeding stage without any coupling condenser. This point of connection is determined, for instance, by assuming the condenser 101 to charge to a value of approximately 30 volts, and then when potential is applied at the terminal I02 at a time when the charge is acquired by the condenser I01 there is a voltage of 330 volts between the control electrode and the positive terminal at the designated point. Furthermore, it is to be seen that the point 5 is taken such that it is a point of 0 volt D.-C. so that the A.-C. transmission is approximately 90% of the total voltage and still the control electrode N4 of the amplifier 12 is maintained at 0 volts 11-0. and no new or additional distortion can be introduced in that section of the amplifier. This is particularly useful and ample for very low sweep frequencies where with the conventional resistance capacity coupling difiiculties arise due to limited size of the time constant provided by the coupling. Frequency variation is carried out bya change of the accelerated voltage bias rather than changes in the leakage resistance I I3 which may be set once and for all and fixes the variation range. By making the valueof the resistor N3 of proper order frequency variations of greater than one to twelve may be obtained where the resistor is of the order of 0.2 x ohms and of the order of about 1 to 5.with the resistor N3 of a smaller value, e. g., about 60,000 ohms, whereas the change in frequency will be only of the order of about 1 to 3 with a simple variation of the leakage resistance without a change in the bias.

Having described my invention, what I claim is:

1. An oscillator for developing substantially non-distorted linw: voltage waves of sawtooth form comprising a thermionic element including at least a cathode, a control electrode and an anode, a limiting impedance element connected between the cathode and a point of fixed potential, terminal means for connecting to a positive terminal of a source of voltage, and a transformer winding connected intermediate the said terminal means and the anode of said thermionic device so that positive voltage is fed to the said thermionic device through said transformer winding, a series combination comprising a resistor and a capacitor connected in parallel with all of said transformer winding, said thermionic device and said cathode impedance and having one terminal of the said capacitor connected to the said point of fixed potential, and a feedback connection including a transformer winding coupled to said first named transformer winding connected between the control electrode of said thermionic device and the junction of said serially connected resistor andcondcnser. I

2. An oscillator for developing substantially non-distorted linear voltage waves of sawtooth form comprising a thermionic element including at least a cathode, a control electrode and an anode, a limiting resistor element connected'be tween the cathode and a point of fixed potential, terminal means for connecting t a positive terminal of a source of voltage, and a transformer winding connected intermediate the said terminal means and the anode of said thermionic device so that positive voltage is fed to the said thermionic device through said transformer winding,

a series combination comprising a resistor and a capacitor connected in parallel with all of said transformer winding, said thermionic device and said cathode resistor and having one terminal of the said capacitor connected to the said point of fixed potential, and a feedback connection including a transformer winding coupled to said first named transformer winding connected between the control electrode of said thermionic device and the junction of said serially connected resistor and condenser.

3. The oscillator claimed n claim 1 comprising, in addition, means for supplying synchronizing impulses to the triode input circuit to control the cycle of oscillation.

4. An oscillator for developing substantially non-distorted linear voltage waves of sawtooth form comprising a thermionic element including at least a cathode, a control electrode and an anode, a limiting resistor element connected between the cathode and a point of fixed potential, terminal means for connecting to a positive terminal of a source of voltage, and a transformer winding connected intermediate the said terminal means and the anode of said thermionic device so that positive voltage is fed to the said thermionic device through said transformer winding, a series combination comprising a variable resistor and a capacitor connected in parallel with all of said first named transformer winding, said thermionic device and said cathode resistor and having the said capacitor connected with one terminal thereof to the said point of fixed potential, and a feedback connection including a transformer winding coupled to said first named transformer winding connected between the control electrode of said thermionic device and the junction of said series connected variable resistor and condenser.

5. The oscillator claimed in claim 4 comprising, in addition, means connected to the said limiting resistor for applying synchronizing impulses to said oscillator to control the period of oscillation thereof.

6. The oscillator claimed in claim 1 comprising, in addition, means connected to the said cathode impedance for applying synchronizing impulses to said oscillator to control the period of oscillation thereof.

7. An oscillator for developing substantially non-distorted linear voltage waves of sawtooth form comprising a first thermionic element including at least a cathode, a control electrode and an anode, a limiting impedance element connected between the cathode and ground, terminal means for supplying positive voltages to the anode of said tube, and a transformer winding connected in the anode supply and intermediate the said terminal and the said anode, a plurality of condenser elements of. predetermined graduated sizes, resistance means connected to the said terminal means for supplying charging current to said condensers, switching means for connecting said condensers individually serially between said charging resistance means and ground, a second transformer winding having one end thereof connected to the control electrode of said tube and the other end connected intermediate the said charging resistance and said condensers and coupled to the first named transformer winding to provide feedback between the anode circuit and the control electrode, a second switching 'means connected to operate jointly with said first named switching means for varying the eifective cathode connected limiting impedance of said tube with changes in the connection of the said condensers connected to be charged through said resistor means, an amplifying tube comprising at least a cathode, a control electrode and an anode with the said anode connected to said terminal means and the said cathode connected toground, and a galvanic connection from an intermediate point on said charging resistor to said control electrode for supplying control voltages of a wave form corresponding to the voltages across said connected condenser to said amplifying tube.

8. The oscillator claimed in claim 7 comprising, in addition, means for supplying control voltages to said cathode impedance of said first named tube for controlling the period of charge and discharge of said condensers whereby the frequency of the developed sawtooth waves is controlled.

9. An oscillator for developing substantially non-distorted linear voltage waves of sawtooth form comprising a pair of terminal points across which a source of voltage is adapted to be connected, a first series circuit including a transformer primary winding, a limiting impedance and a thermionic tube having a cathode, a control electrode and an anode connected between said terminal points, a second series circuit comprising a resistor and a condenser connected between said terminal points, and a bridging connection including the secondary winding of a transformer coupled to the said primary winding connected between the control electrode of said thermionic tube and the junction point of the condenser and resistor oi the second named series circuit.

10. An oscillator for developing substantially non-distorted linear voltage waves of sawtooth form comprising a pair of terminal points across which a source of voltage is adapted to be connected, a first series circuit including a transformer primary winding, a limiting impedance and a thermionic tube having a cathode, a control electrode and an anode connected between said terminal points, a second series circuit comprising a resistor and a condenser connected between said terminal pointa'and a bridging connection including the secondary winding of a transformer coupled to the said primary winding connected between the control electrode of said thermionic tube and the junction point of the condenser and resistor of the second named series circuit, and means. for supplying control impulses upon the impedance element included in the first named series circuit to control the oscillation cycle of charge and discharge of said condenser element of the second series circuit.

11. An oscillator for developing substantially non-distorted linear voltage waves of sawtooth form comprising a first thermionic element including at least a ctahode, a control electrode and an anode, a; limiting impedance element connected between the cathode and ground, terminal means for supplying positive voltages to the anode of said tube, and a transformer winding connected in the anode supplyand intermediate the said terminal and the said anode, a plurality of condenser elements of predetermined graduated sizes, resistance means connected to the said terminal means for supplying charging current to said condensers, switching means for connecting said condensers individually serially between said charging resistance means and ground, a second transformer winding having one end thereof connected to the control electrodeof said tube and the other and connected intermediate the said charging resistance and said condensers and coupled to the first named transformer winding to provide feedback between the anode circuit and the control electrode, and a second switching means connected to operate jointly with said first named switching means for varying the effective cathode connected limiting impedance of said tube with changes in the connection of the said condensers connected to be charged through said resistor means.

KURT SCHLESINGER.