US2244230A - Circuit arrangement for television receivers - Google Patents

Circuit arrangement for television receivers Download PDF

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Publication number
US2244230A
US2244230A US261384A US26138439A US2244230A US 2244230 A US2244230 A US 2244230A US 261384 A US261384 A US 261384A US 26138439 A US26138439 A US 26138439A US 2244230 A US2244230 A US 2244230A
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United States
Prior art keywords
impulse
potential
frame
line
tube
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Expired - Lifetime
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US261384A
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English (en)
Inventor
Andrieu Robert
Brandle Heinrich
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Telefunken AG
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Telefunken AG
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Publication date
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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

  • a circuit arrangement for television receivers has already been proposed in which the sawtooth generator for the line scanning is blocked for the duration of the synchronizing impulse for the vertical or frame deflection of the oathode ray beam.
  • the frame deflection is hereby understood to mean the deflection in the slow image coordinate (vertically), whereby the transmission may be one with the ordinary line sequence, or a line skip transmission.
  • the blocking was carried out in accordance with the older suggestion to'the'e'n'd that after completion of the synchronizing impulse for frame deflection, i. e., at the setting-in of'the line impulse for the new line, there will be obtained within a possibly short time period the built-up state of operation in the line saw-tooth generator.
  • a potential shall be produced during the entire duration of this current flow through which the channel will be blocked in which the frame impulse and the line impulse can produce a'control potential at the said tube and which potential also blocks the line saw tooth generator proper.
  • FIGS 1, 2 and 3 show various schematic forms of receiving systems.
  • FIG. 1 shows a system in accordance with the present system.
  • Figures 5a and 512 show operation curves.
  • Figure 6 shows a modification of a portion of Figure 4
  • Figures 7 and 8 show curves of operation relating to Figure 6.
  • a high frequency amplifier or intermediate frequency amplifier lll' feeds into a detector circuit H having connected thereto a separation arrangement l2 which separates the impulse mixture from the image content.
  • a branch off point P is in back of the separation device and from which a chan; nel leads across a frequency selection circuit with following amplitude selection stage l3 to the frame or vertical saw-tooth generator l4 and another channel to the line saw-tooth generator l5.
  • this latter channel an arrangement for separating the frame'impulse can be inserted but this is not shown in Figure 1.
  • the blocking according to the invention is therefore to act ahead of the branch off point P if it is to be effective for both channels, or it should act in back of the point P in each individual channel.
  • the frequency selection circuit i3 with following amplitude selection stage is connected to the line saw-tooth generator !5 and the blocking is to act at the line saw-tooth generator but at no later place. As compared with this it would not be sufficient in the sense of the invention to have the blocking act in i3 in Figure 1, or in if! or 13 in Figure 2, and in It in Figure 3.
  • FIG. 4 A mode of construction according to the invention is shown in Figure 4 of the drawings.
  • item I6 is a transformer across which a detector circuit is fed with the high frequency potential or intermediate frequency potential modulated with the image content and with the synchronizing impulses.
  • Item I1 is a detector tube and I8 and I9 represent two loads resistors each having connected in parallel thereto a respective smoothing condenser 20 and 2] respectively.
  • gap synchronizing synchronous impulses in the direction which is blacker than black by interruption of the carrier wave, i. e. positive transmission
  • the potential for the control grid 22 of the image reproducing Braun tube 23 can be derived immmediately at the left end of the resistor 18.
  • Item 24 designates a self blocking oscillation generator feeding across the line 25 the end tube of the line saw-tooth generator.
  • a further self blocking oscillation generator for the frame deflection is designated by 26 and is fed at the screen grid with the mixture of line impulses and frame impulses formed by the frequency selection circuit 21.
  • the frequency selection arrangement 21 is fed from the right end of the resistor i9 whereby an amplitude selection stage l2" for the, separation of the synchronizing impulses from the image content lies ahead of the frequency select-ion arrangement ( Figure 2), or whether only a single amplitude selection stage l2 for the separation of the image and impulses is employed and the impulse mixture is obtained from the line saw-tooth generator l'5 ( Figure 3).
  • the saw-tooth generator for the frame deflection consists in addition to the blocking oscillator circuit 2B of the resistors 28 and 29 and condenser 30.
  • the condenser 30 will be charged across the resistors 28 and 29, and this condenser will be discharged during the plate current impulses in the blocking oscillator 26. Then a potential increasing in a linear fashion appears during the period of the frame deflection at the upper layer of the condenser 30 to which the frame deflection coil can be connected across a tube, or to which the deflection plates for the frame deflection coordinate are connected across a push-pull amplifier.
  • the resistor 29 serves in a manner known as such for producing an impulse shaped voltage component during the pause in the frame deflection, said voltage component being added to the saw-tooth potential at the condenser 30 in order to produce a non-distorted saw-tooth de flection despite the self inductance of the deflection coil or of the distributed capacity of the leads of the deflection plates.
  • the potential drop through the resistor 29 has the direction indicated by the plus and minus signs in Figure 4.
  • this potential pattern is applied to the screen grid of the blocking oscillator 26 without the insertion of an amplitude selection stage containing a special tube, the plate current pattern in the blocking oscillator which has a longer time period than the frame impulse, could be disturbed by the line impulse or line impulses following the frame impulse and by the corresponding potential pattern at the frequency selection circuit. This is due to the fact that the plate current of a-screen grid tube depends in fact on the screen grid potential while this screen grid potential is determined by the potential at the frequency selection circuit.
  • a condenser 32 may be placed in parallel to the resistor 29 such as shown in Figure 6 (which is a portion of Figure 4) and the time constant of 29 and 32 can be so chosen that the potential at the upper end of the resistor has approximately the pattern shown in Figure 8 instead of the pattern in the circuit according to Figure 4 as shown in Figure '7.
  • the circuit described in reference to the Figures 4 and 6 not only may be employed for the method of gap synchronization, but also for the case in which the synchronizing impulses lie in the direction blacker than black and are transmitted by an amplitude larger than the image content (negative transmission).
  • the circuit according to Figure 4 it is necessary simply to connect to the left end of the resistor I8 the blocking oscillator for the line deflection and to connect the control grid 22 of the cathode ray tube to the right end of the resistor I9. Otherwise all other deliberations hitherto made remain unchanged.
  • the described return blocking is not only of advantage when using a blocking oscillator circuit in the frame or vertical deflection generator, but also in every case in which the frame deflection generator contains a tube circuit which, following the excitation by the changed frame impulse, furnishes a current impulse whose course can still be influenced by potential variations applied from the outside.
  • the frame deflection generator contains a tube circuit which, following the excitation by the changed frame impulse, furnishes a current impulse whose course can still be influenced by potential variations applied from the outside.
  • There belongs among these tube circuits also for instance a tube relaxation circuit having two discharge tubes coupled in opposition across a resistancecondenser combination.
  • a cathode ray picture reproducing tube having a control electrode, means for applying the received pic ture and synchronizing signals to the control electrode with the synchronizing signals extending in a negative direction, a horizontal deflection voltage generating means, means for applying the received signals to the horizontal deflection voltage generating means with the synchronizing signals extending in a positive direction to control the frequency of operation of the generating means, a vertical deflection voltage generating means including a resistance and a condenser,
  • a cathode ray picture reproducing tube a horizontal deflection voltage generating means, means for applying the received signals to the horizontal deflection voltage generating means to control the frequency of operation of the generating means, a vertical deflection voltage generating means including a resistance, a condenser and an impedance, means for connecting the resistance, condenser and impedance across a source of potential, means for intermittently discharging said condenser to develop potential impulses across said impedance, and means to apply the developed potential impulses to the horizontal deflection voltage generating means whereby the horizontal deflection voltage means may be discontinued for a few cycles of its operation during the discharge of the condenser.
  • a cathode ray picture reproducing tube having a control electrode, means for applying the received picture and synchronizing signals to the control electrode with the synchronizing signals extending in a negative direction, a horizontal deflection voltage generating means, means for applying the received signals to the horizontal deflection voltage generating means with the synchronizing signals extending in a positive direction to control the frequency of operation of the generating means, a vertical deflection generating means including a condenser, means including a resistance for connecting one plate of the condenser to a source of positive potential, means including an impedance for connecting the other plate of the condenser to a point of fixed potential, means to intermittently discharge said condenser, to develop potential impulses across said impedance, and means to apply the developed potential impulses to the horizontal voltage generating means and to the control electrode of the cathode ray tube whereby a horizontal deflection voltage generating means, means for applying the received signals to the horizontal deflection voltage generating means with the synchronizing signals extending in

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Details Of Television Scanning (AREA)
US261384A 1937-07-01 1939-03-11 Circuit arrangement for television receivers Expired - Lifetime US2244230A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE211746X 1937-07-01
DE140338X 1938-03-14

Publications (1)

Publication Number Publication Date
US2244230A true US2244230A (en) 1941-06-03

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Family Applications (1)

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US261384A Expired - Lifetime US2244230A (en) 1937-07-01 1939-03-11 Circuit arrangement for television receivers

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US (1) US2244230A (fr)
CH (1) CH211746A (fr)
FR (1) FR839984A (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2632799A (en) * 1949-03-03 1953-03-24 Zenith Radio Corp Decoding apparatus for television receivers

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2632799A (en) * 1949-03-03 1953-03-24 Zenith Radio Corp Decoding apparatus for television receivers

Also Published As

Publication number Publication date
FR839984A (fr) 1939-04-17
CH211746A (de) 1940-10-15

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