USRE23206E - fyler - Google Patents

Description

Ressued Mar. 14, 1950 SAW-TOOTH VOLTAGE GENERATOR George W. Fyler, Lombard, Ill.,

assigner to Motorola, Inc., Chicago, Ill., a corporation of Illinois riginal No. 2,458,366, dated January 4, 1949, Serial No. 29,250, April 10, 1948, which is a division of Serial No. 696,129, September 11, 1946. Application for reissue December l, 1949, Serial 7 Claims.

This invention relates generally to television receivers and in particular to a power supply system for producing the voltages required for operation of a television receiver including a cathode ray tube. This application is a division of my application Serial No. 696,129, filed September ll, 1946.

In prior television receivers it has been necessary to use relatively large amounts of current at high voltage to provide energy for operation of the cathode ray receiver tube and for deflecting the electron beam thereof. Also in most television receivers a relatively large number of amplifying stages are required which also draw current at high voltage. For the above reasons a power supply network has been necessary which is capable of producing very high voltages, and to provide such a supply a relatively large power transformer has generally been provided. Such a power transformer is objectionable because of the high cost thereof and also because of the size and weight added to the receiver.

Heretofore television receivers of conventional design have required power inputs of 300 watts or more. The large amount of power required prevented the placing of a receiver in a small cabinet because of the difficulty of keeping the components reasonably cool. Also hum effects from the power supply are more pronounced when the power transformer is near the picture tube. This further prevented placing the television receiver in a small cabinet.

An object of this invention is to provide a small television receiver having simple and efficient means for providing the potentials required for operation of the television receiver tube.

Another object of this invention is to provide an inexpensive television receiver having a power supply system which does not require a power transformer to reduce the cost of the receiver and to eliminate hum in the picture normally produced by the transformer.

A feature of this invention is the provision of a television receiver having a power network which does not require a power transformer.

A further feature of this invention is the provision of a horizontal deflection generator which operates from relatively low voltage direct current and produces a sawtooth output having a relatively large amplitude.

Further objects. features and advantages will be apparent from a consideration of the following description taken in connection with the accompanying drawing in which a schematic diagram of a television receiver utilizing the hori- (Cl. Z50-36) Matter enclosed in heavy brackets lappears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue 2 zontal deflection generator in accordance with the invention is shown.

In practicing my invention I provide a television receiver of the superheterodyne type capable of receiving modulated composite video signals and sound signals and deriving video, synchronization, and sound signals therefrom. A simplified power supply network is used in which selenium rectiers are used for energizing a system which operates at relatively low Voltages. A horizontal deflection generator is provided which operates from the low voltage power supply and produces a sawtooth voltage of relatively high magnitude for causing the horizontal deflections of the electron beam. This is accomplished by reversely charging condensers so that a sawtooth voltage is developed thereacross.

In the drawings a schematic diagram of a television receiver of the superheterodyne type is shown. The various components of the receiver which are not a part of this invention are shown by block diagrams and the function thereof indicated therein. These components will not be described in detail but will be referred to in such a manner that the operation of the television receiver will be apparent. The receiver includes an antenna circuit 24 which may include a suitable antenna such as a dipole. The signals picked up by the antenna circuit are then amplified in the tuned radio frequency amplifier 28. A local oscillator 3| is provided for producing oscillations for converting the radio frequency signals into intermediate frequency signals in converter 34. Switching means for these units may be ganged together so that by a single operation, the antenna, radio frequency amplifier, and oscillator are tuned to the desired frequencies.

For the purpose of selectively amplifying the intermediate frequencies, an intermediate frequency amplifier 36 is provided. The video and sound intermediate frequency signals are both passed through the intermediate frequency amplifler 36 and are separated after passing through the video amplier as is explained in my cepending application Serial No. 676,651, filed June 14. 1946, subject Television receiver circuit. The amplified intermediate frequency signals are applied to detector 4D wherein the video and sound frequency signals are derived. These signals are then amplified in video amplifier 42. The amplied video and sound signals are separated in the video and sound separation circuit M with the video signal being applied to the cathode ray tube I5 and the clipper Tl, and the sound signal being applied to the limiter 50. The sound signal is then applied to the discriminator and audio amplier 53 and is reproduced in loud speaker |4.

The composite video signal is applied to the cathode 6| of the cathode ray tube I5. The control grid 62 of the tube may be connected to the negative side of the power supply and the cathode may be biased with respect thereto through variable resistor 64, the resistor being variable to control the intensity of the cathode ray beam and thereby the brightness of the image produced. Electrostatic deiiection is utilized in the tube, the vertical deflection being controlled by plates 66 and 69 and horizontal deflection by the plates 10 and 1|. Potentials for causing vertical deflection are applied to the plates by vertical deection generator 12 and potentials for horizontal deection are produced by horizontal deflection generator 13. The clipper functions to derive the synchronization pulses from the composite video signal, the derived pulses being applied to the generators 12 and 13 to control the sawtooth voltage Waves produced thereby.

The television receiver in accordance with the invention is adapted to be energized from the standard ||0 volt alternating current household power supply. In order to provide the power required for operation of the television receiver energy must be available for supplying the heaters for the cathodes of the various tubes and also high potential direct current of various voltages must be available for providing the plate and screen voltages necessary for the tubes and for providing the potentials required for focusing and deiiecting the beam of the cathode ray tube. The power supply system in accordance with the invention includes terminals |00 and |0| adapted to be connected to a source of 110 volts alternating current, a power switch |02 being included for controlling the energization of the system. The connection from terminal |0| continues through switch |02 to a pair of selenium rectiilers |32 and |33. The selenium rectiiiers are connected so that the positive portion of the alternating current cycle is rectified by rectifier |32 and appears across condenser |34 which is connected between the rectifier |32 and the terminal |00 which forms the other side of the alternating current source. The rectifier |33 is connected to pass only negative currents so that a negative potential appears across condenser |35 connected between rectifier |33 and the common terminal. It is apparent that there will be relatively large 60 cycle ripple in the voltages across each of the condensers |34 and |35. However, the ripple in the voltages will be out of phase so that the combined p0- tential across the two condensers `will have a 120 cycle ripple which will be of much smaller magnitude than the 60 cycle ripple across each condenser. It is obvious that by completely eliminating the center wire the 60 cycle ripple would be thereby eliminated. However, substantially the same effect can be obtained by retaining the center wire and placing a relatively large resistor |36 therein to reduce the effect of the 60 cycle ripple. Resistors |31 and |38 are provided in the positive and negative wires and condensers |39 and |40 are provided across the positive and negative branches, respectively, of the power supply to provide stable operating potentials. Although the power supply system is illustrated as connected only to the horizontal deflection generator 13, it is apparent that it can also be used to energize the other components of the television receiver.

Referring now more specifically to the horizontal deflection generator 13, the generator includes a triode tube 82 which functions as a blocking oscillator. The tube includes a cathode |50, grid |5| and plate |52. The plate and gridare connected to the windings |53 and |54 of a transformer in a manner to provide regeneration therebetween. A damping resistor |61 is shown connected across Winding |53 and a similar damping resistor may be provided across winding |54. The grid is also connected to couplingr condenser 6| to receive synchronization pulses therefrom. The negative side of the power supply network is connected through choke coil |55 to the cathode and the plate is connected to the positive wire through choke coil |56 and variable resistor |49. The coils and |56 are mounted on a common core and are so wound and connected that the inductance between points |63 and |64 is a maximum. It is seen that the total power supply voltage can be applied to the horizontal deflection generator, or the voltage can be reduced by resistor |49 to reduce thereby the amplitude ofiy the 'gen/eratqrgutput. The frequency of the oscill lator can-be controlled by changing the bias on; grid |5| as by adjusting resistor |51. Condenser' |59 acts as a by-pass for resistor |51. A series circuit is provided between the terminals of the power supply through the choke coils |55 and |56 and condensers |60, |6| and |62. The coils are preferably identical and as they are wound so that the inductances thereof are additive, the total inductance is four times that of either coil. In order that the system is balanced the total capacitance of the condensers |60 and I6| in series is made substantially equal to the capacitance of condenser |62 and the common connection therebetween is connected to the center wire of the power supply. The two condensers |60 and |6| are provided so that a sawtooth voltage of smaller amplitude can be derived from terminal |60 if desired, as for exciting a high voltage power supply.

In operation, the blocking oscillator circuit, including windings |53 and |54`the condensers |60, |6| and |62 and the stray circuit capacities, is adjusted toa high frequency substantially five times that of the horizontal synchronization pulses'. More specifically, when the tube 82 conducts, a series circuit is formed through winding |53 and condensers |60, |6| and |62 which is resonant at a frequency substantially five times that oi' the horizontal synchronization pulses. The choke coils |55 and |56 and condensers |60, I6| and |62 are so chosen that the series circuit through these components will be resonant at a relatively low frequency, a frequency one-tenth that of the horizontal scanning frequency being suitable. As the coil |56 is connected to the positive Wire of the power supply and the coil |55 is connected to the negative wire, the current through this circuit will cause the condensers |60, |6| and |62 to charge so that the point |63 becomes positive and the point |64 becomes negative. It is noted that this will cause a positive potential on the plate |52 which tends to cause the tube to conduct. When the tube 82 conducts a heavy plate current will flow through the high frequency series resonant circuit producing current through the condensers |60, |6| and |62 in an opposite direction to that produced by the power supply. The transfer of energy through the windings |53 and |54 will render the tube 82 highly conductive. The blocking oscillator circuit is arranged so that the tube 82 will conduct 1| for one-half cycle which will cause the point |63 to become negative and the point 64 to become positive. Said tube therefore operates as a circuit charging means. As the natural frequency of the series circuit through the chokes and condensers is relatively slow the voltage thereacross will build up linearly until interrupted when the tube 82 conducts. This provides the trace portion of the cycle. The bias of the oscillator will be adjusted so that the tube is just about to conduct when a synchronization pulse is received so that the pulse will start the retrace action. As the natural frequency of the blocking oscillator is very fast the retrace period will be fast as is desired. If the frequency of the oscillator is ve times the frequency of the horizontal pulses as stated, since the retrace is only one-half a cycle the time required ior the retrace would be one-tenth of the total time of one horizontal deflection cycle. The reversing potentials on points |63 and |64 are applied through condensers |65 and |66 to the horizontal deflecting plates 1U and 1I, respectively. rI`he voltage appearing on each plate will swing from positive to negative values and vice versa to thereby provide a relatively large balanced sawtooth voltage across the deflecting plates and 'I I.

In a specic model constructed in accordance with the invention, with standard 110 volt alternating current power applied to the terminals Illu and IUI of the power supply, voltages of approximately 130 volts were produced between the positive and negative wires and the center wire of the power supply, thus making the total voltage between the negative and positive wires approximately 260 volts. When using one section of a 12SN7 tube as the blocking oscillator in the horizontal deection generator 13, and applying the entire 260 volts thereto, voltages varying plus and minus approximately 300 volts were obtained across the sides of the horizontal deflection generator circuit thereby providing a sweep voltage having an amplitude of 600 volts for deection y of the cathode ray beam in a horizontal direction. This voltage was ample for operating a seven inch direct viewing cathode ray tube such as type 7GP4.

As previously stated, horizontal synchronization pulses are applied to the generator from the clipper 11 through coupling condenser 6| to the grid |51 of tube 82. This signal is applied across the winding |54 of the blocking oscillator transformer which acts as a filter to further select the horizontal synchronization pulses. By properly tuning the coil |54 a series resonant circuit having a very sharp characteristic can be provided.

It is seen from the above that I have provided a simple horizontal deflection generator which is effective to provide balanced sawtooth 4voltages of relatively high amplitude from a low voltage power supply source. Only a single triode tube section is required in the generator so that the cost thereof is very small. The trace portion of the voltage wave is linear and the retrace portion is relatively fast so that the resulting wave is highly satisfactory for providing deection voltages.

Although I have illustrated one specific embodiment of my invention, it is apparent that various changes and modiiications can be made therein which fall within the intended scope of the invention as defined in the appended claims.

I claim:

[1. In a television receiver including a cathode ray tube having horizontal and vertical deflection electrodes for deecting the electron beam ot' said tube and means for deriving synchronization pulses for controlling the deflection of said beam. a generator for providing Still/.tooth voltages for said horizontal deection electrodes comprising an electron discharge valve having input and output electrodes, a transformerhaving a pairof winding s aplurality"of condensers, a pair of equal inductances, a source of potential, said inductances and condensers being connected in series across said source of potential, said input and output electrodes of said valve being coupled through said windings of said transformer, said output electrodes of said valve being connected across said condensers so that the voltage built up on said condensers because of current flowing from said source of potential is applied thereto, said valvebeingnarranged to conduct when a predetermined potential is applied to.v said output electrodes to provide current through said condenser ii-'direction opposite to the current flow caused by said source of potential to thereby charge said condensers in the opposite direction, and means for applying said synchronization pulses to the input terminals of said valve to cause said valve to conduct at a predetermined time] [2. A voltage generator adapted to produce a sawtooth voltage wave comprising condenser means, a pair of equal closely coupled inductances, a source of potential, and a blocking oscillator including an electron discharge valve, said inductances and said condenser means being connected in series across said source of potential and being of such value that a series circuit resonant at a relatively low frequency is provided for charging said condenser means in one direction, said electron discharge valve being connected across said condenser means and being biased to conduct when a predetermined potential is applied thereto, said blocking oscillator having a relatively high frequency and being ar: ranged vsgmthat'saidvalve.is blocked after an os'cillation of ohalf cycle duration so that said con densefnjeans isdischarged and then charged in the einen@ directiva] [3. A voltageMgene'ator adapted to produce a sawtooth voltage wave comprising condenser means, a pair of equal closely coupled inductances, a source of potential, and a blocking oscillator including an electron discharge valve, said inductances and said condenser means being connected in series across said source of potential for charging said condenser means in one direction, said inductors providing a steady charging current whereby said condenser means charge to a voltage greater than the voltage of said source, said electron discharge valve being connected across said condenser means and being biased to conduct when a predetermined potential is applied thereto, said blocking oscillator having a relatively high frequency and being arranged so that said valve is blocked after an oscillation of onehalf cycle duration so that said condenser means is discharged and then charged to substantially the same voltage in the opposite direction] 4. A voltage generator adapted to produce a sawtooth voltage wave comprising condenser means, a pair of equal closely coupled inductances, a Source of potential, and a blocking oscillator including an electron discharge valve, said inductances and said condenser means being connected in series across said source of potential for charging said condenser means in one direction, said inductors providinga steady charging current whereby said condenser means charge to a voltage greater than the voltage of said source, said blocking oscillator being connected across said condenser means for applying the voltage on said condenser means t said valve, said blocking oscillator and said condenser means forming` a series circuit resonant at a relatively high frequency when said valve conducts, said valve being blocked after an oscillation of one-half cycle duration so that said condenser means is discharged and then charged to substantially the Ysame voltage in the opposite direction, so that the sawtooth voltage Wave developed. across said condenser means has an amplitude variation greater than twice the voltage of said source. d

[5. A voltage generator adapted to produce sawtooth voltage wave of a predetermined frequency comprising, a plurality of condensers, a pair of equal closely coupled inductances, a source of potential, and a blocking oscillator including an electron discharge valve, said inductances and condensers being connected in series across said source of potential and being of such value that the series circuit is resonant at a frequency of the order of one-tenth that of said predetermined frequency, said electron discharge valve being connected across said condensers so that the voltage built up on said condensers because of current flowing from said source of potential is applied thereto, said valve being biased to conduct when a predetermined potential is applied thereto to cause current to ow through said condensers in a direction opposite to the current now caused bysaid source of potential, said blocking oscillator having a frequency of the order of five times that of said predetermined frequency and being arranged so that said valve conduits during an oscillation of one-half cycle so that said condensers are rapidly discharged and then charged in the opposite direction] [6. A sawtooth voltage generator comprising condenser means, a pair of equal closely coupled inductances a source of potential, and a blocking oscillator including an electron discharge valve having input and output electrodes and a transformer having windings coupling said electrodes, said condenser means being connected intermediate said inductances in series across said source of potential, said output electrodes of said valve being connected in series with one of said transformer windings across said condenser means so that the voltage built up thereacross is applied to said valve, said valve being biased to conduct when a predetermined potential is applied thereto to provide a high frequency series resonant circuit through said condenser means and said one winding permitting the flow of current through said condenser means in a direction opposite to current fiow caused by said source of potential, said transformer providing energy to said input electrodes to render said valve highly conducting, said valve being blocked when an oscillation of one-half cycle has taken place so that said condenser means is discharged and then charged in the opposite direction] [7. A sawtooth voltage generator comprising a plurality of condensers, a pair of equal inductances, a source of potential, and a blocking oscillator including an electron discharge valve having input and output electrodes and a transformer having a pair of windings coupling said electrodes, said inductances and said condensers being connected in series across said source of potential, said output electrodes of said valve being connected across said condensers so that the voltage built up thereacross because of current flowing from said power supply is applied to said valve, said valve being biased to conduct when a predeterminated potential is applied thereto to provide current through said condensers in a direction opposite to current ilow caused by said source of potential, said blocking oscillator being arranged so that transfer of energy through said transformer from said output electrodes to said input electrodes blocks said valve when an oscillation of one-half cycle has taken place to discharge said condensers and then charge said condensers in the opposite direction] [8. A voltage generator adapted to produce a sawtooth voltage wave comprising, condenser means, a pair of equal closely coupled inductances, a source of potential, and a blocking oscillator including an electron discharge valve, said inductances and said condenser means being connected in series across said source of potential and being of such value that a series circuit resonant at a relatively low frequency is provided so that voltage is built up on said condenser means at a uniform rate to provide a substantially linear trace, said electron discharge valve being connected across said condenser means so that the voltage thereon is applied to said valve to render said valve to conduct when said voltage reaches a predetermined value, said blocking oscillator being tuned to resonate with said condenser means at a relatively high frequency to form a high frequency resonant circuit through which said condenser means discharges when said valve conducts, said valve being blocked after an oscillation of one-half cycle duration so that said condenser means is rapidly discharged and then charged in the opposite direction to provide a fast retrace.

[9. A voltage generator adapted to produce a sawtooth voltage wave of a predetermined frequency comprising, condenser means, a pair of equal closely coupled inductances, a source of potential, and a blocking oscillator including an electron discharge valve, said inductances and said condenser means being connected in series across said source of potential and being of such value that the series circuit is resonant at a frequency of the order of one-tenth that of said predetermined frequency, so that voltage is built up on said condenser means at a uniform rate to provide a substantially linear trace, said blocking oscillator being connected'across said condenser means so that the voltage on said condenser means is applied to said electron discharge valve to cause said valve to conduct when said voltage reaches a predetermined value, said blocking oscillator being tuned to resonate with said condenser means at a frequency of the order of ive times that of said predetermined frequency when said valve conducts, said valve being arranged to conduct for an oscillation of onehalf cycle so that said condenser means is rapidly discharged and kthen charged in the opposite direction to provide a fast retrace] [10. A sawtooth voltage generator adapted to produce sawtooth voltage waves comprising, a pair of equal condenser means, a pair of equal closely coupled inductances, a source of potential, and a blocking oscillator including an electron discharge valve, said condenser means being connected intermediate said inductances in series across said source of potential and being of such value that a series circuit resonant at a relatively low frequency is provided so that voltage is built up on said condenser means at a uniform rate to provide a substantially linear trace, said blocking oscillator being connected across said condenser means so that the voltage on said condenser means is applied to said valve to cause said valve to conduct when said voltage reaches a predetermined value. said blocking oscillator being tuned to reson: te with said condenser means at a relatively high frequency and arranged so that said valve conducts for one-half cycle so that said condenser means is rapidly discharged and then charged in the opposite direction to provide a fast retrace, whereby balanced sawtooth voltage waves are developed across said pair of condenser means] [11. In a television receiver including a cathode rayvtube having horizontal and vertical deflectin 4 electrodes for deflecting the electron beam of said tube and means for deriving synchronization pulses for controlling the deflection oi' said beam, a generator for providing sawtooth voltages for said horizontal deflection electrodes comprising a pair of condenser means. a pair of equal inductances, a source of potential, a blocking oscillator including an electron discharge valve and a transformer including a pair of windings, said ind'uctances and condenser means being connected in series across said source of potential, said valve being connected across said condenser means so that the voltage built up thereon because of current flowing from said source of potential is applied to said valve, said valve being arranged to conduct when a predetermined potential is applied to said output electrodes to provide current through said condenser means in a direction opposite to the current flow caused by said source of potential, said blocking oscillator being so arranged that said valve conducts during one-half cycle of said oscillator so that said condenser means are discharged and then charged in the opposite direction, and means for applying said synchronization pulses to said valve across one of said windings to cause said valve to conduct at a predetermined time] 12. In a television receiver including a cathode ray tube having horizontal and vertical deflection electrodes for deiiecting tbe electron beam of said tube and means for deriving synchronization pulses for controlling the deflection of said beam. a generator for providing sawtooth voltages for said horizontal deflection electrodes comprising a plurality of condensers, a pair of eoual inductances, a source of potential, a blocking oscillatorV including anelectron discharge valve having input and output electrodes and a transfoigper having a pair of windings coupling said electrodeshsaid inductances and condensers being connectedin series across said source of potential, said output electrodes of said valve being connected across said condensers so that the voltage built up thereacross because of current flowingfrom said source of potential is applied to said valve, and means for applying said synchronization pulses across one of said windings to said input electrodes to cause said valve to conduct to provide current through said condenser in a direction opposite to the current flow. .caused by said source oiV potentiai, Asaid one winding. being tu ried tg act agfilter for said synchroniza tion pulsesfad blocking oscillator being so arranged that transfer of energy" through said transformer blocks said valve when an oscillation of one-half cycle has taken place.

[13. The method of producing a sawtooth voltage wave across condenser means which is connected to a blocking oscillator including an electron discharge valve and a transformer having primary and secondary windings, said method comprising the steps of, charging said condenser means to one polarity at a uniform rate, discharging said condenser means and storing energy therefrom in said primary winding, transferring energy from said primary winding to said secondary winding to render said valve more conductive, charging said condenser to the polarity opposite to said one polarity by the energy stored in said primary winding, and utilizing said valve to prevent transfer of current between said primary winding and said condenser means for a succeeding linear charging step] [14. A sawtooth voltage generator circuit for producing a sawtooth voltage wave of one frequency comprising, condenser means, means for charging said condenser means at a uniform rate, an electron discharge valve having input and output electrodes, a transformer having primary and secondary windings, said output electrodes of said valve and said primary winding being connected across said condenser means and forming a series circuit thereby in which oscillation can take place when said valve conducts, said series circuit being resonant at a frequency at least five times said one freouencv, said secondary winding being connected to said input electrodes of said valve to transfer energy thereto for rendering said valve more conductive] [15. A sawtooth voltage generator circuit comprising. condenser means, means for charging said condenser means at a uniform rate. an electron discharge valve having input and output electrodes, a transformer having primary and secondary windings, said output electrode of said valve and said primary winding being connected across said condenser means and forming a series resonant circuit thereby in which oscillations can take place when said valve conducts, said secondary windings being connected to said input electrodes of said valve to transfer energy thereto for rendering said valve more conductive] 16. A sawtooth voltage generator circuit for producing a sawtooth voltage wave of one frequency comprising, condenser means, means for charging said condenser means at a uniform rate, an electron discharge valve having input and output electrodes. a transformer having primary and secondary windings, a damping resistor connected across said primary winding.. said output electrggep of said valve and said primary winding eing connected across said condenser means and forming a series circuit thereby in which oscillations can take place when said valve con' ducts, said series circuit being resonant at a frequency at least five times said one frequency. said secondary winding being connected to said input electrodes of said valve to transfer energy thereto for rendering said valve highly conductive.

[17. A sawtooth voltage generator circuit for producing a sawtooth voltage wave of one frequency comprising, condenser means, means for charging said condenser means at a uniform rate, and a blocking oscillator including an electron discharge valve and a transformer having a pair of windings, said valve being connected in series with one of said windings to said condenser means and forming a series circuit in which oscillations can take place when said valve conducts, said series circuit being resonant at a frequency at least flve times said one frequency,

said one vinding providing energy to said bloei'- ine oscillator to render said valve more conductive, said valve operating to disconnect said inductance means from said condenser means when said resonant circuit has completed one-half cycle of an oscillation] 18. A sawtooth voltage generator circuit for producing a sawtooth voltage wave of a predetermined frequency comprising condenser means having at least two terminals. means including inductance means connected in series with said condenser means for charging said condenser means at a uniform rate, a blocking oscillator including an electron discharge valve. a transformer and frequency controlling means for said oscillator, said valve having a cathode, a plate. and a grid. said transformer having primary and secondary windings. and a damping resistor connected across said primary winding. said primary winding being connected directly between said plate of said valve and one terminal of said condenser means. said cathode of said valve being connected directly to the other terminal of said condenser means. said secondary winding being connected in series` with .said freand the capacity of said condenser means being it so related that the series circuit formed thereby when said valve conducts is resonant at a frequency at least five times said predetermined frcquency.

19. A sawtooth voltage generator circuit for :"7

producing a sawtooth voltage wave having trace and retrace portionsv said generator comprising condenser means having at least two terminals. a source of potential, means including inductance means connecting said condenser means to said source of potential for charging said condenser means at a uniform rate to a voltage greater than the voltage of said source to thereby form said trace portions of said sawtooth voltage wave. a blocking oscillator including an electron discharge valve, a transformer and frequency controlling means. said valve including a cathode. a plate. and a grid, said transformer including primary and secondary windings, and a damping resistor connected across said primary winding. said primary winding being connected directly between said plate of said valve and one terminal of said condenser means, said cathode of said valve being connected directly to the other terminal of said condenser means, said secondary winding being connected in series with said frequency controlling means between said grid and said cathode of said valve to transfer energy to said grid -for rendering said valve highly conductive, a closed series circuit consisting of said primaryiwinding, said condenser means and the plate-cathode path of said valve being formed in which oscillations of one-half cycle take place when said valve conducts to reverse the charge on said condenser means and thereby form the retrace portions of said sawtoothnvoltage. wave.

20. A sawtooth voltage generator circuit for producing a sawtooth voltage wave of one frequency comprising, condenser means, means for charging said condenser means at a uniform rate. an electron discharge valve having input and output electrodes, a transformer having primary and secondary windings, a damping resistor connected across said primary winding, said output electrodes of said valve and said primary winding being connected in series directly across said condenser means so that when said valve conducts a closed series circuit consisting of said primary winding and said condenser means is formed in which an oscillation of one-half cycle takes place to discharge said condenser means and charge the same to the opposite polarity, the inductance of said primary winding and the capacity of said condenser means being so related that said series circuit is resonant at a frequency at least jive times said one frequency, said secondary winding being connected to said input electrodes of said valve to transfer energy thereto for rendering said valve highly conductive.

21. A sawtooth voltage generator circuit for a television receiver which includes a cathode ray tube having horizontal and vertical dejiection electrodes for deflecting the electron beam of the tube and means for deriving synchronization pulses for controlling the deflection of the beam, said sawtooth voltage generator circuit producing a sawtooth voltage wave having trace and retrace portions, said generator comprising condenser means having at least two terminals. a 'source of potential, inductance means connecting said condenser means to said source of potential for charging said condenser means at a uniform rate to a voltage greater than the voltage of said source to thereby form said trace portions of said sawtooth voltage wave. a blocking oscillator including an electron discharge valve, a trans formerand frequency controlling means, said electron dischargeifalveliiigcathd, a plate, and a grid, said transformer having primary and secondary windings, a. damping resistor connected across said primary winding, said primary winding being connected directly between said plate of said valve and one terminal of said condenser means, said cathode of said valve being connected directly to the other terminal of said condenser means, said secondary winding being connected in series with said frequency controlling means between said grid and said cathode of said valve for transferring energy to said grid, and means for applying synchronization pulses across said secondary winding for renderingV said valve conductive, said primary winding. said condenser means and the plate-cathode path of said valve together forming a closed'series circuit in which oscillations of one-half cycle take place when said valve conducts =to reverse the charge on said condenser means and form the retrace portions of said sawtooth voltage wave.

GEORGE W. FYLER,

REFERENCES CITED The following references are of record in the le of this patent or the original patent:

Edson et al Dec. 10. 1946

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