US2433342A - Cathode-ray tube sweep circuit - Google Patents

Cathode-ray tube sweep circuit Download PDF

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Publication number
US2433342A
US2433342A US489884A US48988443A US2433342A US 2433342 A US2433342 A US 2433342A US 489884 A US489884 A US 489884A US 48988443 A US48988443 A US 48988443A US 2433342 A US2433342 A US 2433342A
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US
United States
Prior art keywords
circuit
valve
cathode
waves
saw
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US489884A
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English (en)
Inventor
Chatterjea Prafulla Kumar
Ambrose Dermot Min
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
STC PLC
Original Assignee
Standard Telephone and Cables PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Standard Telephone and Cables PLC filed Critical Standard Telephone and Cables PLC
Application granted granted Critical
Publication of US2433342A publication Critical patent/US2433342A/en
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Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N3/00—Scanning details of television systems; Combination thereof with generation of supply voltages
    • H04N3/10—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical
    • H04N3/16—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical by deflecting electron beam in cathode-ray tube, e.g. scanning corrections
    • H04N3/24—Blanking circuits
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K4/00—Generating pulses having essentially a finite slope or stepped portions
    • H03K4/06—Generating pulses having essentially a finite slope or stepped portions having triangular shape
    • H03K4/08—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape
    • H03K4/10—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape using as active elements vacuum tubes only
    • H03K4/26—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape using as active elements vacuum tubes only in which a sawtooth current is produced through an inductor
    • H03K4/28—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape using as active elements vacuum tubes only in which a sawtooth current is produced through an inductor using a tube operating as a switching device
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K4/00—Generating pulses having essentially a finite slope or stepped portions
    • H03K4/06—Generating pulses having essentially a finite slope or stepped portions having triangular shape
    • H03K4/08—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape
    • H03K4/10—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape using as active elements vacuum tubes only
    • H03K4/26—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape using as active elements vacuum tubes only in which a sawtooth current is produced through an inductor
    • H03K4/28—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape using as active elements vacuum tubes only in which a sawtooth current is produced through an inductor using a tube operating as a switching device
    • H03K4/32—Generating pulses having essentially a finite slope or stepped portions having triangular shape having sawtooth shape using as active elements vacuum tubes only in which a sawtooth current is produced through an inductor using a tube operating as a switching device combined with means for generating the driving pulses

Definitions

  • the present invention relates to electro-magnetic scanning arrangements in television tubes and in particular concerns means for eliminating undesired oscillations during the fly-back stroke.
  • the present invention overcomes these diiilculties by shunting the coil with the anode circuit of an ordinary hard valve normally biassed beyond the cut-ofl, so that it presents a substantially infinite impedance. Just at the end of each deflection stroke or the saw-tooth wave an impulse is applied to the control grid of the valve so that it becomes conducting and damps the coil during the period of the fly-back stroke,
  • the damping valv has no effect on the saw-tooth waves and therefore cannot produce distortion.
  • the invention accordingly provides a scanning arrangement for a television tube comprising a generator of saw-tooth waves, an inductive circuit for applying the waves to the electron beam of the tube, and a hard valve normally biassed beyond the cut-oi! and having its anode circuit connected to shunt the inductive circuit,
  • means being provided for unblocking the valve only during the periods of the fly-back strokes of the saw-tooth waves.
  • FIG. 1 01' the accompanying drawing shows a schematic circuit diagram of one embodiment of For explaining its action reference will be made to the waveformdiagrams of Fig. 2.
  • Fig. 1 there is shown an inductive circuit L which is intended to represent the means for applying scanning waves to a television tube (not shown).
  • the circuit L may comprlsethe usual deflecting coils or may include atransformer used for supplying the waves to the deflecting coils or plates of the tube, or may com- Excepting at prise any arrangement the impedance of which has similar characteristics.
  • This circuit will gen erally have in addition self-capacity, and the apparatus and leads connected thereto will generally introduce some capacity, so that the circuit L will in efl'ect be shunted by a condenser represented by C in Fig. 1.
  • a parallel resonant circuit is thus formed, and the impulse which is in effect applied at each turn oscillations unless the circuit is sufllciently heavily damped.
  • the circuit L is supplied with waves from a saw-tooth generator G (which may be operated from an impulse generator or synchronised with incoming waves in the usual way by arrangements not shown), through an amplifying valve V1, the circuit L being connected in series with the anode circuit of the valve.
  • V is an ordinary hard valve
  • the anode circuit of V is connected across L with the cathode at the end nearest to the anode of V1.
  • the valve V2 is supplied with saw-tooth waves from G grids of V and V: are shown biased from eonventlonal batteries B1 and B: through grid resistances R1 and R2, and the saw-tooth waves are applied from (5i through condensers C1 and C3.
  • valves V3 and V are shown coupled by a transformer T, the primary winding P of which is 7 connected in series with the anode of V3, and
  • the secondary winding is connected between the control grid and cathode of V2, a conventional biassing battery B: being included as shown.
  • the control grid of V is shunted by a condenser C3 whose function will be explained later.
  • Positlve potential for the anodes of V1 and V3 is obtained from th terminalHT and is'supplied through L and P respectively.
  • the potential of the battery B should be so chosen that the valve V: isbiassed beyond the cut-off for the maximum potential which can appear across the circuit L, so that there can be no appreciable anode current.
  • the anode circuit impedance is thus substantially infinite.
  • curve A represents the voltage wave applied from the generator G to the control grid of valve V3.
  • the voltage rises from zero to +E and then flies back very nearly instantaneously to zero again.
  • the negative potential of the battery B3 should be so chosen that the valve is substantially blocked until the applied potential has risen to some value +(E-e), where e is small compared with E, so that no plate current flows except just at the end lily-back stroke may pro- The control.
  • the condenser C2 is provided to delay the blocking of the valve Vz until after the fly-back stroke is completed. It will be clear that on removal of the voltage applied from the valve V3, the condenser will take a short time to discharge through the resistance of the coil S and will maintain the the valve V2 above the cut-ofi value for a short period after the time of the fiy-back stroke.
  • Curve C in Fig. 2 shows the grid voltage Eg of the valve V2, the peaks being approximately symmetrical. The valve V2 is thus unblocked for a short period t which embraces the fly-back stroke, and could generally be about equal to the fly-back time.
  • the damping valve has no eflect at all on the waves except just at the time of the fly-back stroke, and the saw-tooth waves themselves are used to condition the damping valve at the right time so that it operates only when required.
  • triode valves have been shown for simplicity the invention is not confined to the use of such valves, which can have any number of electrodes. Any suitable biassing arrangements may be used to replace the batteries B1, B2 and B: which are conventional,
  • valve V itself it not absolutely essential, as the waves could 4 be applied direct from G to V2 (no phase reversal being then necessary), but it is preferable to include V8 in order to obtain a large amplitude at the control grid of V2, so that it can be sharply blocked and unblocked.
  • a sweep generator adapted to be triggered by suitable synchronizing pulses and having a sweep voltage output varying in the general manner of a saw-tooth, means for applying said sweep output to an inductive circuit, a high vacuum tube having at least a cathode, grid and an anode, a condenser connected across the input circuit to said high vacuum tube, said condenser having sufiicient capacity to maintain said grid above cut-off after said grid has reached cutoff potential, for a predetermined time, connections to shunt said tube across a.
  • circuit including said inductive circuit so that said inductive cir .cuit may be completed through said tube, means for feeding the output of said sweep generator to an amplifier stage, said amplifier stage having a transformer primary in the output thereof, a secondary for said transformer connected between the cathode and control grid of said high vacuum tube, means for biasing said control grid below cut-off, said bias being sufficient to prevent said control grid from rising above cut-off only when said saw-tooth voltage has reached a predetermined peak value whereby said tube discharges said inductive circuit in predetermined phase relationship to said sweep.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Details Of Television Scanning (AREA)
US489884A 1942-07-24 1943-06-07 Cathode-ray tube sweep circuit Expired - Lifetime US2433342A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB10371/42A GB558927A (en) 1942-07-24 1942-07-24 Improvements in or relating to television

Publications (1)

Publication Number Publication Date
US2433342A true US2433342A (en) 1947-12-30

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
US489884A Expired - Lifetime US2433342A (en) 1942-07-24 1943-06-07 Cathode-ray tube sweep circuit

Country Status (4)

Country Link
US (1) US2433342A (en, 2012)
BE (1) BE479720A (en, 2012)
FR (1) FR939252A (en, 2012)
GB (1) GB558927A (en, 2012)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2612633A (en) * 1950-09-13 1952-09-30 Bell Telephone Labor Inc Multiplex converter
US2797265A (en) * 1953-03-31 1957-06-25 Rca Corp Pulse amplifier
US2848557A (en) * 1952-03-22 1958-08-19 Wurlitzer Co Automatic volume level control for phonographs

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2170847A (en) * 1935-06-08 1939-08-29 Rca Corp Electron beam deflection circuits
US2315073A (en) * 1941-05-01 1943-03-30 Bell Telephone Labor Inc Electric circuits

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2170847A (en) * 1935-06-08 1939-08-29 Rca Corp Electron beam deflection circuits
US2315073A (en) * 1941-05-01 1943-03-30 Bell Telephone Labor Inc Electric circuits

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2612633A (en) * 1950-09-13 1952-09-30 Bell Telephone Labor Inc Multiplex converter
US2848557A (en) * 1952-03-22 1958-08-19 Wurlitzer Co Automatic volume level control for phonographs
US2797265A (en) * 1953-03-31 1957-06-25 Rca Corp Pulse amplifier

Also Published As

Publication number Publication date
BE479720A (en, 2012)
GB558927A (en) 1944-01-27
FR939252A (fr) 1948-11-09

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