US2165770A - Electrical control apparatus - Google Patents

Electrical control apparatus Download PDF

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Publication number
US2165770A
US2165770A US722843A US72284334A US2165770A US 2165770 A US2165770 A US 2165770A US 722843 A US722843 A US 722843A US 72284334 A US72284334 A US 72284334A US 2165770 A US2165770 A US 2165770A
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United States
Prior art keywords
tube
grid
impulses
oscillator
circuit
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Expired - Lifetime
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US722843A
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English (en)
Inventor
William A Tolson
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RCA Corp
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RCA Corp
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Publication date
Priority to NL43288D priority Critical patent/NL43288C/xx
Application filed by RCA Corp filed Critical RCA Corp
Priority to US722843A priority patent/US2165770A/en
Priority to FR788484D priority patent/FR788484A/fr
Application granted granted Critical
Publication of US2165770A publication Critical patent/US2165770A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/04—Synchronising
    • H04N5/12—Devices in which the synchronising signals are only operative if a phase difference occurs between synchronising and synchronised scanning devices, e.g. flywheel synchronising
    • H04N5/123—Devices in which the synchronising signals are only operative if a phase difference occurs between synchronising and synchronised scanning devices, e.g. flywheel synchronising whereby the synchronisation signal directly commands a frequency generator

Definitions

  • My invention relates tovelectrical control apparatus and more particularly to methods of and means for maintaining synchronous operation in television systems and the like.
  • vertical framing impulses contain sufiicient energy to make the action of the vertical saw-tooth wave generator dependent upon the amplitude and shape of a framing impulse. This is especially objectionable in television systems employing interlaced scanning since the scanning lines of one picture frame should fall between the lines of a preceding frame with all the lines equally spaced apart.
  • the difference in the amplitude and/or shape of the successive framing impulses may be due to various causes, but in an interlaced scanning system the main reason for such diiference is the fact that alternate framing impulses have the adjacent horizontal synchronizing impulse a difierent time interval away in order to produce the interlaced scanning efiect.
  • the apparatus for transmitting a picture having interlaced scanning is no part of my invention, no description of it will be given.
  • the result of alternate framing impulseshaving different wave shapes is that the interlaced scanning lines at the receiver tend to pair, Accordingly, either the lines are prominent in the picture or picture detail is lost.
  • a still further object of my invention is to provide a television receiver in which positive synchronizing action is obtained without the use of manually operated adjusting devices.
  • a still further object of my invention is to provide a television receiver in which the saw-tooth wave oscillators need not be constructed within close limits for satisfactory synchronization.
  • a still further object of my invention is to provide improved means for reshaping an electrical impulse.
  • driver tube In practicing my invention, instead of impressing the framing impulses directly upon the oscillator of the vertical deflecting circuit at the receiver, I interpose between the said oscillator and the synchronizing input what will be referred to as a driver tube.
  • the driver tube is so connected with .an associated circuit that it will operate to produce a sharp voltage impulse in response to the application of a suitable voltage impulse to its control grid.
  • the driver tube is so connected that it will start to oscillate in .response to, and only in response to, the reception of a synchronizing impulse. Also, the adjustment is such that after each synchronizing impulse, the driver tube assumes its normal inactive state.
  • each framing impulse causes a sharp voltage impulse to appear in the output circuit of the driver tube for controlling the oscillator of the deflecting circuit, this voltage impulse containing much less energy than the framing impulse and so little energy that changes in its amplitude and/or wave shape will have substantially no effect upon the oscillator.
  • Fig, 1 is a circuit and a block diagram of a television receiver embodying my invention
  • Fig. 2 is a set of curves which are referred to in explaining the operation of my invention.
  • Figs. 3 and 4 are circuit diagrams of other embodiments.
  • the invention is shown applied to a television receiver in which a radio receiver and an amplifier 3 receive and amplify incoming television signals and impress them upon the control-grid 1 of a cathode-ray receiver tube 5. Both picture signals and synchronizing impulses are impressed upon this control grid.
  • the synchronizing impulses are separated from the picture signals by means of a suitable separating circuit indicated at 9 before being applied to the deflecting circuits.
  • This separating circuit also separates the horizontal synchronizing impulses from the framing impulses, the horizontal synchronizing impulses being supplied to a saw-tooth wave generator indicated at H for supplying saw-tooth current to the horizontal deflecting coils
  • the framing impulses are supplied through a conductor I5 and a potentiometer H to the vertical deflecting circuit.
  • the saw-tooth wave generator for supplying saw-tooth current to the vertical deflecting coils IQ of the cathode-ray tube 5 comprises an oscillator 2
  • is illustrated as a blocking oscillator although it should be understood that in place of a blocking oscillator, other types of oscillators, such as oscillators of the Dyna-tron or multivibrator types, may be employed.
  • comprises an electric discharge tube 21 of the suppressor grid type which has a cathode 23, a control grid 3
  • is connected through a fixed grid leak resistor 39 and a variable grid leak resistor 4
  • the grid circuit of the oscillator also includes a grid condenser 43, the secondary winding 45 of the transformer 41, and a section of a potentiometer 49, connected in series between the control grid 3
  • the anode 31 is connected through the primary 5
  • the coupling thus provided between the plate and grid circuits is such that, as the plate current through the primary winding 5
  • causes a flow of grid current which charges the grid condenser 43 in a direction such that it tends to make the control grid negative.
  • the plate current reaches a maximum value and then decreases, at the same time reversing the direction of the induced voltage in the grid circuit whereby the control grid is made so negative that the tube is biased beyond cut-off.
  • the grid condenser 43 has been charged suflicarialy to bias the control grid 3
  • the oscillator may be made to oscillate at the desired picture or frame frequency.
  • the oscillator is adjusted to as in cillate at a frequency somewhat lower than the desired frequency in order to permit synchronization. For example, if 60 picture frames per second are desired, the oscillator may be so adjusted that it tends to oscillate at 57 cycles per second.
  • the synchronizing signals are impressed upon the oscillator through a driver tube 53 which may be of the suppressor grid type including a cathode 55, a control grid 51, a screen grid 59, a suppressor grid BI, and an anode 63.
  • the driver tube 53 is so connected that it would function as a blocking oscillator except for the fact that it is normally biased beyond cut-off.
  • the control grid 51 is connected through a grid-leak resistor and a biasing battery 61 to ground and through ground tothe cathode 55.
  • the grid circuit also includes a grid condenser 69 which is connected in series with a winding 1
  • the plate circuit of the driver tube 53 is coupled to its grid circuit through a winding 15 of the transformer 13, the anode 63 being supplied with positive potential through this transformer winding.
  • and 15 is such that, except for the biasing battery 61, the tube would oscillate as a blocking oscillator the same as oscillator 2
  • the potential applied to the control grid 51 by the biasing battery 61 is suiiicient, however, to bias the driver tube beyond the cut-off point whereby it is inactive until a synchronizing impulse is impressed thereon.
  • the transformer is provided with a third winding 11 which has the potentiometer 49 connected thereacross for impressing a portion of the voltage output of the driver tube upon the blocking oscillator circuit.
  • the blocking oscillator is connected across only a small percentage of the potentiometer 49 as indicated by the potentiometer values which are given in the drawings by way of example.
  • the above-described circuit operates to produce voltage impulses in the blocking oscillator circuit 2
  • this control is obtained by adjusting the oscillator 2
  • are impressed upon the tube 23 which is provided for the purpose of so altering the shape of the voltage impulse that a perfect saw-tooth current will be supplied to the deflecting coils l3.
  • This change in wave shape is obtained by means of a condenser 19 and a reslstor 3
  • the deflecting coils I9 are connected to the output circuit of the output tube 25 through a direct current connection including the variable tap 83 and resistors 85 for properly centering the cathode-ray beam on the fluorescent screen of the tube 5, and through an alternating current or impulse connection which includes a bypass condenser 81.
  • the driver tube 53 is so adjusted that, with the fixed grid bias removed, it will oscillate to produce positive votage peaks which have a smaller time interval between them than do the vertical synchronizing impulses. That is, the interval between t2 and ta (Fig. 2) is less than the interval between framing impulses.
  • the reason for this adjustment is that it permits all the charge to leak ofi the grid condenser 69 and so return the driver tube to its original state before the next framing impulse occurs. This prevents the action of the driver tube during the reception of one framing impulse from being influenced by a preceding framing impulse.
  • time interval between i2 and ta should be great enough to prevent a single framing impulse from causing the driver tube to break into oscillation more than once
  • this adjustment which is referred to as a speed control adjustment, is made by varying the grid leak resistor 4
  • a speed control or frequency adjustment of the vertical deflecting circuit in order to simplify the operation of the receiver. This may be accomplished by employing a circuit, such as illustrated in Fig. 3, in which an amplifier tube 93 is employed for preventing reaction of the oscillator on the driver tube. While the circuit shown in Fig. 3 and the vertical deflecting circuit shown in Fig. 1 may be identical except for the addition of the coupling tube 93, several variations have been illustrated. In the two figures, like parts have been indicated by the same reference numerals.
  • the driver tube may comprise an electric discharge tube 95 having a cathode 91, a control grid 99 and an anode IOI.
  • the control grid 99 is connected through a gridleak resistor I03 and a biasing battery I05 to ground and through ground to the cathode 91, the biasing battery I05 applying a negative bias to the grid 99 for biasing the tube beyond cutofi.
  • a grid-leak condenser I01, the secondary I09 of a transformer III and the lower section of the synchronizing input potentiometer I1 areconnected in series between the control grid 99 and ground.
  • the plate circuit of the tube 95 is coupled to the grid circuit by means of the primary II3 of the transformer III. As in Fig. 1, this coupling and the constants of the driver tube circuit' are so adjusted that the driver tube would oscillate to supply voltage impulses if it were not for the biasing battery I05.
  • the blocking oscillator comprises an electric discharge tube II5 having a cathode H1, a control grid H9 and an anode I2I.
  • the control grid H9 is connected through a winding I23 of a transformer I25 and a grid-leak resistor I21 to ground, and through ground to the cathode III.
  • the grid-leak resistor I21 is shunted by a grid condenser I29 which charges up to apply a negative potential to the control grid II9 during a portion of the operating cycle as explained in connection with the blocking oscillator shown in Fig. 1.
  • the plate circuit of the tube is coupled in the proper phase relation to the grid circuit by means of a winding I3I of the transformer I25.
  • the voltage impulses appearing in the output circuit of the driver tube 95 are impressed upon the blocking oscillator circuit through the electric discharge tube 93, which has a cathode I33, a control grid I and an anode I31.
  • the anode Ill of the driver tube 95 is coupled to the control grid I35 of the coupling tube 93 through a coupling condenser I39.
  • the control grid I35 is maintained at a negative potential sufficient to bias tube 93 beyond cut-off by means of a biasing battery I which has its positive terminal connected to the cathode I33 through ground and its negative terminal connected to the grid I35 through a grid leak resistor I43.
  • the output circuit of the coupling tube 93 is coupled to the blocking oscillator circuit through a third winding I45 on the transformer I25. It will be understood that the winding I45 is wound or connected in such a direction that a synchronizing impulse in the output of the tube 93 makes the grid II9 of the blocking oscillator II5 less negative.
  • the tube 93 may be biased to function as an ordinary class A amplifier. By biasing the tube 93 beyond cut-off, however, extraneous voltages which might interfere with proper synchronization of scanning are eliminated.
  • the blocking oscillator H5 is coupled to the impulse tube 23 for supplying a voltage wave to the input circuit of the output tube 25 of the proper wave form for producing a saw-tooth current in the vertical deflecting coils.
  • the blocking oscillator .I I5 may be coupled to the impulse -tube 23 in the way shown in Fig. 1, or it may be coupled thereto by means of a direct conection from the grid II9 of the blocking oscillator tube to the grid I41 of the impulse tube 23 through a conductor I49, as shown in Fig. 3.
  • the main distinction between these two coupling connections is that in Fig.
  • the control grid of the impulse tube 23 derives a suitable biasing potential from the grid circuit of the oscillator tube II5 instead of from its own grid-leak resistor as in Fig. 1.
  • the bias on the impulse tube 23 is suflicient to bias it beyond cut-off. It will be noted that because of the voltage drop in the plate resistor I46, a grid voltage insufficient to bias tube Hi to cut-off does bias tube 23 to cutoff.
  • the oscillator may be adjusted to oscillate at a frequency as low as cycles per second and it will be pulled into the synchronism by the synchronizing impulses. Not only does this permit the elimination of a speed control" adjustment, but it also insures that a receiver will synchronize properly even through some slight change or variation has been made in the oscillator circuit. Such changes or variations may result from replacing a defective oscillator tube or they may occur during the manufacture of the receivers as an unavoidable result of quantity production methods.
  • Fig. 4 there is illustrated a circuit of the Dynatron type in which the tube is properly biased to function as a driver tube for a saw tooth wave generator.
  • Figs. 1 and 4 like parts are indi cated by the same reference numerals.
  • the driver tube comprises an electric discharge tube I50 having a cathode I5I, a control grid I53, 2. screen grid I55, and an anode I51.
  • the anode I5! is connected through an inductance coil I59 to a source of potential such as a battery I6I while the screen grid I55 is connectedto a point of higher potential on the battery I6I such that the tube would oscillate as a Dynatron relaxation oscillator if the grid I53 were connected directly to the cathode I5I.
  • the grid I53 is negatively biased by a biasing source such as a battery I63, the bias being suflicient to bias the tube I50 to cut-oil. Therefore, the tube I50 will start to oscillate only in response to the appearance of a synchronizing impulse across the resistor I1 and will reach an inactive state before the occurrence of the next synchronizing impulse. As in' the case of the circuit of the blocking oscillator type, the tube I50 converts a framing impulse into a sharp voltage impulse containing a small amount of energy.
  • combination apparatus for converting a plurality of electrical impulses having a certain characteristic and occurring at regularly spaced time intervals into a plurality of electrical impulses having a different characteristic
  • said apparatus including an oscillator of the self-oscillatory type comprising an electric discharge tube of the high vacuum type having a plurality of electrodes, means for causing said oscillator to oscillate and then become inactive in response to the application of a certain potential to one of said electrodes, the time interval between the start of said oscillation and the instant the tube becomes inactive being less than said regularly spaced time intervals and being greater than the duration of each of said first impulses, means for applying said certain potential to said one electrode in response to the occurrence of each of said first impulses, means for producing recurring electrical waves of saw-tooth shape in response to recurring electrical waves being impressed thereon, and means for impressing the impulses produced by said apparatus upon said last means.
  • apparatus for reshaping an electrical impulse comprising an electric discharge tube having a cathode, a control grid, and a plate, a condenser and a grid leak resistor connected between said control grid and said cathode to form a grid circuit, said tube having an output circuit including said plate, means for so coupling said output circuit to said grid circuit that said grid is made less negative in response to an increase in plate current, means for so biasing saidgrld that said tube is maintained biased beyond the cut-off point until said impulse is impressedupon said grid circuit from an outside source, means for impressing said impulses upon said grid circuit, and an oscillator which oscillates freely in an uncontrolled condition, said apparatus and said oscillator being so.
  • the method of synchronizing which comprises separating said horizontal synchronizing impulses from said vertical synchronlzing impulses at the receiver by a filtering action whereby said vertical impulses only may,
  • a saw-tooth wave generator which includes a self-oscillatory oscillator, means for converting synchronizing impulses containing a certain amount of energy into impulses having an amplitude at least as great as the amplitude of the first impulses but containing less ener y, said means including an electric discharge tube of the high vacuumptypefhaving a plurality of electrodes and including means for, causing said tube to oscillate momentarily and then become inactive in response to the appliflcation to one of said electrodes of one of said synchronizing impulses, and means-for impressing said converted impulsesupon said. oscillator whereby said saw-tooth waves are produced in synchronism with said synchronizing impulses.
  • Apparatus for converting periodically recurring electrical impulses each having a certain amplitude and energy content into periodically recurring electrical impulses each having an amplitude at least as great as said certain amplitude and an energy content less than said certain energy content comprising a high vacuum electric discharge tube having a plate, a cathode and a control grid, a transformer having a primary and a secondary, a grid circuit connected between said grid and said cathode and including said secondary, a plate circuit conductive to direct current connected between said plate and said cathode and including said primary, said plate and grid circuits being coupled through said transformer in such phase as to produce oscillations, a condenser in said grid circult in series with said secondary for storing a charge to block said tube, a grid resistor and a biasing voltage source in series with each other and in parallel to said condenser whereby a charge may leak off said condenser, said biasing source being connected in the correct polarity and the biasing voltage being of sufficient magnitude to block said tube

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Details Of Television Scanning (AREA)
US722843A 1934-04-28 1934-04-28 Electrical control apparatus Expired - Lifetime US2165770A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
NL43288D NL43288C (enrdf_load_stackoverflow) 1934-04-28
US722843A US2165770A (en) 1934-04-28 1934-04-28 Electrical control apparatus
FR788484D FR788484A (fr) 1934-04-28 1935-04-06 Appareil de contrôle électrique

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Application Number Priority Date Filing Date Title
US722843A US2165770A (en) 1934-04-28 1934-04-28 Electrical control apparatus

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US2165770A true US2165770A (en) 1939-07-11

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US722843A Expired - Lifetime US2165770A (en) 1934-04-28 1934-04-28 Electrical control apparatus

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FR (1) FR788484A (enrdf_load_stackoverflow)
NL (1) NL43288C (enrdf_load_stackoverflow)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2441334A (en) * 1943-04-30 1948-05-11 Du Mont Allen B Lab Inc Signal level and phase control
US2444782A (en) * 1942-10-31 1948-07-06 Gen Electric Pulse generating circuits
US2483431A (en) * 1944-05-10 1949-10-04 Sperry Corp Blocking oscillator
US2485101A (en) * 1944-12-30 1949-10-18 Raytheon Mfg Co Pulse generator
US2495938A (en) * 1947-06-07 1950-01-31 Hazeltine Research Inc Signal generator
US2509792A (en) * 1946-05-17 1950-05-30 Raytheon Mfg Co Blocking oscillator trigger circuit
US2556027A (en) * 1948-02-06 1951-06-05 Philco Corp Relaxation oscillator
US2597092A (en) * 1946-09-19 1952-05-20 Motorola Inc Vertical sweep generator
US2957245A (en) * 1957-05-29 1960-10-25 Creighton B Kimble Electronic reticle generator
US3012232A (en) * 1953-01-27 1961-12-05 Remington Rand Inc High speed printer

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2444782A (en) * 1942-10-31 1948-07-06 Gen Electric Pulse generating circuits
US2441334A (en) * 1943-04-30 1948-05-11 Du Mont Allen B Lab Inc Signal level and phase control
US2483431A (en) * 1944-05-10 1949-10-04 Sperry Corp Blocking oscillator
US2485101A (en) * 1944-12-30 1949-10-18 Raytheon Mfg Co Pulse generator
US2509792A (en) * 1946-05-17 1950-05-30 Raytheon Mfg Co Blocking oscillator trigger circuit
US2597092A (en) * 1946-09-19 1952-05-20 Motorola Inc Vertical sweep generator
US2495938A (en) * 1947-06-07 1950-01-31 Hazeltine Research Inc Signal generator
US2556027A (en) * 1948-02-06 1951-06-05 Philco Corp Relaxation oscillator
US3012232A (en) * 1953-01-27 1961-12-05 Remington Rand Inc High speed printer
US2957245A (en) * 1957-05-29 1960-10-25 Creighton B Kimble Electronic reticle generator

Also Published As

Publication number Publication date
NL43288C (enrdf_load_stackoverflow)
FR788484A (fr) 1935-10-10

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