US2459278A - Device for converting a saw-toothshaped voltage of a comparatively low frequency into a saw-toothshaped current - Google Patents

Device for converting a saw-toothshaped voltage of a comparatively low frequency into a saw-toothshaped current Download PDF

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Publication number
US2459278A
US2459278A US684081A US68408146A US2459278A US 2459278 A US2459278 A US 2459278A US 684081 A US684081 A US 684081A US 68408146 A US68408146 A US 68408146A US 2459278 A US2459278 A US 2459278A
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United States
Prior art keywords
current
saw
sawtooth
toothshaped
voltage
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Expired - Lifetime
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US684081A
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English (en)
Inventor
Haantjes Johan
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Hartford National Bank and Trust Co
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Hartford National Bank and Trust Co
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    • 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
    • H03K4/39—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 an amplifier

Definitions

  • This invention relates to a circuit for converting a sawtooth-shaped voltage of comparatively low frequency into a sawtooth-shaped current in the deflecting coils of a cathode-ray tube preferably serving for the image deflection in a television transmitting or receiving device.
  • this conversion may be effected by means of a discharge tube having a high internal resistance, for example a pentode, the control grid having supplied to it the sawtoothshaped voltage to be converted and having in- 'cluded in its output circuit the deflectingcoils.
  • Fig. 1 is a diagrammatic view.
  • Figures 2a and 2b are graphs illustrating the current as a function of time in the circuit.
  • the image deflectingcoils of a cathode ray tube of which the resistance amounts to T2 and the inductance Lz; are included in the output circuit of a pentode, 2, the grid circuit of which has supplied to it a sawtooth-shaped voltage originating from a source of supply'E.
  • the deflecting coils have connected in parallel to them a choke-coil having a resist ance nand an' inductance Lrand through which flows the direct anode current of the tube V.
  • a condenser C which constitutes a short cir'cuit for the alternating-current component of the output current of the tube V, prevents the direct anode current'from' flowing through the deflecting coils.
  • a comparison of the deformed curve with the ideal curve demonstrates that the deformation substantially occurs during that part of the sawtooth-shaped current which is active for scanning the screen of the cathode ray tube.
  • the said deformation may be suppressed by proportioning the parallelconnected choke coil in such manner that the re sistance to inductance ratio of the choke coil is equal to the resistance to inductance ratio of the deflecting coils.
  • the present invention has for its purpose to provide the minimum value for the choke coil connected in parallel with the deflecting coils, the percentage deviation from linearity during the active part of the sawtooth-shaped current not exceeding a permissible value of about
  • the choke coil is so proportioned as to be approximately equal to 101'2T, in which n represents the resistance of the deflecting coils and T the period of the sawtoothshaped current.
  • the elfect of the invention may be demonstrated as follows, it being taken that the flyback time of the sawtooth-shaped voltage suppliedto the grid of tube 2 and consequently that of the sawtooth-shaped current flowing in the anode circuit of tube V is negligible relatively to the period. This condition is practically always satisfled at low frequencies, in particular with the sawtooth generator in an image deflecting circuit.
  • T-FF' l 2 is a constant factor which is determined by the ratio of the resistances T1 and'rz and s T1+T2 id-L2 is the ratio of the sum of the resistances n and T2 to the sum of the self-inductances L1 and L2,
  • a circuit for converting a relatively low frequency sawtooth voltage into a sawtooth current in the deflecting coils of a cathoderay tube comprising an electron discharge device including a cathode, agrid' and an anode, said device having a high internal resistance, means to apply thesawtooth'voltage asan input tov thegrid of said device, means to couple thedeflecting coils between the anode and cathode of said device, and
  • a choke coil coupled between the anode and cathode of said device, at least a portion of the directcurrent component of the sawtooth output current of said device flowing through said choke coil, the inductance of said choke coil being approximately equal to 10rzT, wherein n represents the resistance of the deflecting coils and T the period of the sawtooth current.
  • a circuit for converting a relatively low frequency sawtooth voltage into a sawtooth current in the deflecting coils of a cathode ray tube comprising a pentode electron discharge device including a cathode, a grid and an anode,
  • a source of anode potential a coupling capacitor, means to apply the sawtooth voltage to said grid, means to couple th deflecting coils between said anode and said cathode in series with said capacitor and said source, and a choke coil connected between said anode and the junction of said source and said capacitor, the inductance of said choke coil being approximately equal to IOrZT, wherein n represents the resistance of the deflecting coils l0 and T the period of the sawtooth current.

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  • Details Of Television Scanning (AREA)
US684081A 1942-03-20 1946-07-16 Device for converting a saw-toothshaped voltage of a comparatively low frequency into a saw-toothshaped current Expired - Lifetime US2459278A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL622656X 1942-03-20

Publications (1)

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US2459278A true US2459278A (en) 1949-01-18

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ID=19788470

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US684081A Expired - Lifetime US2459278A (en) 1942-03-20 1946-07-16 Device for converting a saw-toothshaped voltage of a comparatively low frequency into a saw-toothshaped current

Country Status (4)

Country Link
US (1) US2459278A (fr)
BE (1) BE449723A (fr)
FR (1) FR892604A (fr)
GB (1) GB622656A (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2561586A (en) * 1948-02-11 1951-07-24 Philco Corp Deflection circuit for cathode-ray tubes
US2612620A (en) * 1950-09-09 1952-09-30 Du Mont Allen B Lab Inc Bridge type deflection circuit

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2561586A (en) * 1948-02-11 1951-07-24 Philco Corp Deflection circuit for cathode-ray tubes
US2612620A (en) * 1950-09-09 1952-09-30 Du Mont Allen B Lab Inc Bridge type deflection circuit

Also Published As

Publication number Publication date
GB622656A (en) 1949-05-05
FR892604A (fr) 1944-05-15
BE449723A (fr)

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