US3895252A - Vertical convergence circuit - Google Patents

Vertical convergence circuit Download PDF

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Publication number
US3895252A
US3895252A US352992A US35299273A US3895252A US 3895252 A US3895252 A US 3895252A US 352992 A US352992 A US 352992A US 35299273 A US35299273 A US 35299273A US 3895252 A US3895252 A US 3895252A
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Prior art keywords
signal
vertical scanning
correcting
convergence
transistor
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Expired - Lifetime
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US352992A
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English (en)
Inventor
Katsuo Funakawa
Shuzo Matsumoto
Ryoichi Hirota
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Hitachi Ltd
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Hitachi Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/16—Picture reproducers using cathode ray tubes
    • H04N9/28—Arrangements for convergence or focusing

Definitions

  • v I'LRTICAL CONVERGENCE CIRCUIT Ihis invention relates to a convergence circuit for use in color tele ⁇ ision receivers and more particularly to a dynamic convergence circuit for carrying out desll'ckl regulation of the blue electron beam in the vertical direction in a color picture tube having three electron guns In a color picture tube such as a shadow mask type color picture tube having a plurality of electron guns. It is known that convergence of electron beams of the electron guns throughout the area of the phosphor screen of the color picture tube is difficult to attain and miscomergence as shown in FIG. I occurs commonly.
  • FIG. I shows an example of misconvergence occurring at an upper middle portion. central portion and lower middle portion of the screen and this misconvergence is represented by triangles formed by red.
  • the desired convergence of the three beams can only be attained at the intersection P of the straight broken lines 1 and 2.
  • the beam spot of the blue beam B may be transferred upward in FIG. 2a to attain the desired convergence of the three beams R. (i and B.
  • a correcting current of parabolic waveform whose period is equal to the vertical scanning period T as shown in FIG. 2b may be supplied to the convergence coil for the blue beam.
  • the beam spot of the blue beam B must be transferred downward in FIG. 3a in the direction opposite to the direction shown in FIG. 2a in order to bring the beam spot of the blue beam B to the point P.
  • a parabolic correcting current as shown in FIG. 312 having a polarity opposite to that shown FIG. 21) must be supplied to the convergence coil in order to transfer the beam spot of the blue beam B to the point P thereby attaining the desired convergence.
  • Another object of the present invention is to provide a dynamic convergence circuit for correcting misconvergence in which the misconvergence at an upper portion of the screen of a color picture tube can be corrected independently of the misconvergence at a lower portion of the tube screen. and the blue beam can be transferred in any desired vertical direction.
  • the convergence coil for the blue beam is connected in a bridge circuit so that the amplitude of the correcting current supplied to the convergence coil can be continuously varied and the polarity thereof can also be varied. Further. the parabolic waveform of the correcting current is separated into a waveform corresponding solely to the former half of the vertical scanning period and a waveform corresponding solely to the latter half of the vertical scanning period and these waveforms are applied to independent amplifiers so that their amplitudes can be regulated independently of each other.
  • FIG. I is a diagrammatic view showing misconvergence triangles formed by red, green and blue beams on the screen of a color picture tube;
  • FIG. 2a is a schematic enlarged view of a triangle as shown in FIG. 1;
  • FIG. 2b shows a current waveform required for correcting the blue beam in a misconvergenee tirangle shown in FIG. 211;
  • FIG. 3a is a schematic enlarged view of another form of the triangle
  • FIG. 3b shows a current waveform required for correcting the blue beam in a misconvergence triangle as shown in FIG. 3a;
  • FIG. 4 is a block diagram of an embodiment of the present invention.
  • FIG. 5 shows signal waveforms appearing at various parts of FIG. 4.
  • FIGS. 6a and 6b are circuit diagrams showing two forms of the practical circuitry of the embodiment of the present invention.
  • FIG. 4 is a basic block diagram of a convergence circuit for the blue beam according to the present invention
  • FIG. 5 shows signal waveforms appearing at various parts of the circuit shown in FIG. 4.
  • a parabolic waveform signal whose period is equal to the vertical scanning period is applied to an input terminal 7 of the convergence circuit. and this signal is applied to a pair of separating means 3a and 3b to be separated into a signal corresponding solely to the former half of the vertical scanning period and a signal corresponding solely to the latter half of the vertical scanning period respectively.
  • a train of gate pulses 33 is applied to an input terminal 31 of the separating means 3a and another train of gate pulses 34 is applied to an input terminal 32 of the separating means 3b.
  • the separating means 3a and 312 may be in the form of a switching means which operates in such a manner that the input signal appears at the output thereof during the period of time in which the gate pulse is applied thereto. while such input signal does not appear at the output thereof during the period of time in which no gate pulse appears.
  • These pulse signals 33 and 34 have the same repetition period as the vertical scanning period T.-. are synchronous with the vertical scanning and have a duty factor of 50% However. the pulse signal 33 applied to the gate pulse input terminal 31 of the separating means 30 is 180 out of phase from the pulse signal 34 applied to the gate pulse input terminal 32 of the separating means 3!).
  • the parabolic waveform signal corresponding to the former half of the vertical scanning period and the parabolic waveform signal corresponding to the latter half of the vertical scanning period are applied from the separating means 3a and 3b to respective regulating means 4a and 4b which regulate the amplitude of these signals to the level required for correction and which can freely invert the polarity of these signals as required.
  • These regulating means 4a and 4b are connccted to an output circuit 5 to which a convergence coil 6 for the blue beam is connected
  • a parabolic waveform signal having a repetition period the same as the vertical scanning period T shown by a in FIG. 5 is applied to the input terminal 7 of the convergence circuit.
  • the signal having such a waveform may be obtained by applying to an integrating means the sawtooth waveform signal having the same period as the vertical scanning period derived from the vertical deflection circuit.
  • This parabolic waveform signal is separated by the separating means 3a and 3b into a signal corresponding solely to the former half of the vertical scanning period as shown by b in FlG. 5 and a signal corresponding solely to the latter half of the vertical scanning period as shown by c in FIG. 5. More precisely. the separating means 3a is rendered conductive only during the period of time corrcsponding to the former half of the vertical scanning period in response to the application of the pulse signal 33 to the gate pulse input terminal 31 thereof, and thus.
  • the parabolic waveform signal applied to the input terminal 7 appears at the output of the separating means 30 in the form of an output waveform as shown by b in FIG. 5.
  • the pulse signal 34 having a phase opposite to that of the pulse signal 33 is applied to the gate pulse input terminal 32 ot' the separating means 3b.
  • the parabolic waveform signal applied to the input terminal 7 appears at the output of the separating means 312 in the form of an output waveform as shown by in FIG. 5.
  • the two signals corresponding to the former hall and latter half ofthc vertical scanning period in this manner are applied to regulating means 4a and 4b respectively in which their amplitude and polarity are regulated to be suitable for correction.
  • the two signals thus regulated are applied through the output circuit 5 to the convergence coil 6 for correcting misconvergence of the blue beam.
  • One form of the current waveform flowing through the convergence coil 6 is shown by d in FIG. 5.
  • This example represents the case in which the correcting signals appearing from the respective regulating means 4a and 4b have different amplitudes to deal with the difference between the degrees of misconvergence at the upper and lower portions of the screen.
  • the amplitude of the correcting signal for the former half of the vertical scanning period can be regulated inde pendently of the amplitude of the correcting signal for the latter half of the vertical scanning period.
  • the convergence alignment can be remarkably facilitated due to the fact that convergence alignment for the upper portion of the screen can be attained independently of that for the lower portion of the screen.
  • FIG. 6a shows one preferred form of the practical circuitry of the convergence circuit embodying the present invention.
  • FIG. 6a shows the stages following the separating means 30 and 3b and represents the case in which the regulating means 4a. 4b and the output circuit 5 are unitarily combined.
  • the signal shown by b in FIG. 5 for correcting the misconvergence occurring in the former half of the vertical scanning period or the upper portion of the screen is applied to an input terminal 11.
  • the signal shown by c in FIG. 5 for correcting the misconvergence occurring in the latter half of the vertical scanning period or the lower half of the screen is applied to another input terminal 12.
  • These signals are applied to the base of respective amplifying transistors 13 and 14 which are connected at the collcctor thereof to a bias voltage applying terminal 10.
  • a pair of variable resistors 15 and 16 are provided for regulating the amplitude and polarity of the correcting current supplied to a convergence coil 61 for the blue beam.
  • a capacitor is connected between ground and the emitter of each of the transistors 13 and 14 so as to prevent damage to the transistors 13 and 14 due to direct application of a high voltage which may be induced in the convergence coil 61 and leads therefor due to a spark.
  • a pair of fixed resistors 17 and 13 constitute a bridge circuit together with the variable resistors 15 and 16 so that the direction and amplitude of the correcting current flowing through the convergence coil 61 can be varied depending on the position of the sliding terminal of the variable resistor 15 or 16.
  • the current from the transistor 13 (or 14) is not supplied to the convergence coil 61.
  • the current flows through the convergence coil 61 in one direction or the other depending on the moving direction of the sliding terminal. and the amplitude of the current is increased as the liding terminal approaches either extremity.
  • the parabolic correcting voltage is separated into two portions for correcting the misconvergence occurring in the former half and latter half of the vertical scanning period and such voltages are applied to the base of the respective transistors 13 and 14.
  • a voltage having a waveform as shown by b in FIG. 5 is applied to the base of the transistor l3 and a voltage having a waveform as shown by L' in FIG. 5 is applied to the base of the transistor 14.
  • the amplitude and direction of the emitter current of the transistor 13 can be selected independently of those of the emitter current of the transistor 14 by manipulating the variable resistors 15 and 16, the desired convergence alignment can be easily and simply attained even when the degree of misconvergence at the upper portion of the screen differs from that at the lower portion of the screen. ln an extreme case, the direction of the misconvergence correcting current for the upper portion of the screen can be reversed relative to the direction of such current for the lower portion of the screen.
  • FIG. 6b shows another preferred form of the practical circuitry of the convergence circuit embodying the present invention, and the stages following the separatmg means 3a and 3b are also merely shown as in FIG. but
  • the signal for correcting the misconvergence occurring in the former half of the vertical scanning period is applied to an input terminal 21, and the signal for correcting the misconvergence occurring in the lattcr half of the vertical scanning period is applied to another input tcrminal 22.
  • a pair of variable resistors 25 and 26 are similarly provided for regulating the amplitude and polarity of these correcting signals.
  • a pair of transistors 23 and 24 act to amplify the correcting signals and are connected at the collector thereof to a bias voltage applying terminal 20.
  • a convergence coil 62 for the blue beam is connected across the collectors of the transistors 23 and 24.
  • the operation of the circuit shown in H6. 6/; is basically entirely the same as that of the circuit shown in FIG. 6a except that the amplitude and polarity of the correcting signals are first regulated and then the correcting signals are amplified to be applied to the con vergence coil 62.
  • a dynamic vertical convergence circuit comprising means for producing a signal for correcting misconvergence, said signal being synchronous with the vertical scanning and having the same repetition period as the vertical scanning period; means for separating said correcting signal into a first half signal having a waver form corresponding solely to the former half of the vertical scanning period and a second half signal having a waveform corresponding solely to the latter half of the vertical scanning period; a first transistor having a base supplied with said first half signal, a collector connected to a power supply source, and an emitter; a second transistor having a base supplied with said second half signal, a collector connected to said power supply source, and an emitter; a first variable resistor having a sliding terminal; a second variable resistor having a sliding terminal and connected in parallel with said first variable resistor; a first fixed resistor connected between a point of a reference potential and one of the connecting points of said first and second variable resistors; a second fixed resistor connected between a point of a reference potential and the other connecting point of said first and second

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Video Image Reproduction Devices For Color Tv Systems (AREA)
US352992A 1972-04-28 1973-04-20 Vertical convergence circuit Expired - Lifetime US3895252A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP47042221A JPS494918A (enrdf_load_stackoverflow) 1972-04-28 1972-04-28

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US3895252A true US3895252A (en) 1975-07-15

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US (1) US3895252A (enrdf_load_stackoverflow)
JP (1) JPS494918A (enrdf_load_stackoverflow)
DE (1) DE2321149B2 (enrdf_load_stackoverflow)
NL (1) NL7305846A (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4095137A (en) * 1977-03-18 1978-06-13 Sperry Rand Corporation Digital convergence system for a multi-gun crt
WO1991007047A1 (de) * 1989-11-04 1991-05-16 Deutsche Thomson-Brandt Gmbh Verfahren und vorrichtung zur bildjustierung

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1019888A (en) * 1972-12-29 1977-10-25 General Electric Company Polyetherimides
GB1463298A (en) * 1972-12-29 1977-02-02 Gen Electric Method for making polyetherimide and products produced thereby
JPS5417519B2 (enrdf_load_stackoverflow) * 1974-01-16 1979-06-30
JPS55115174U (enrdf_load_stackoverflow) * 1979-02-09 1980-08-14
JPS5820192B2 (ja) * 1981-02-19 1983-04-21 テクトロニクス、インコ−ポレイテツド コンバ−ジエンス制御装置

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3419748A (en) * 1965-12-23 1968-12-31 Sylvania Electric Prod Convergence waveform-shaping circuitry
US3763391A (en) * 1971-12-29 1973-10-02 Gte Sylvania Inc Color television convergence apparatus
US3766429A (en) * 1971-03-12 1973-10-16 Int Standard Electric Corp Color tv focusing circuit
US3767962A (en) * 1972-01-03 1973-10-23 Warwick Electronics Inc Television convergence system

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3491261A (en) * 1968-05-22 1970-01-20 Rca Corp Dynamic convergence circuits
JPS535774B2 (enrdf_load_stackoverflow) * 1971-12-07 1978-03-02

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3419748A (en) * 1965-12-23 1968-12-31 Sylvania Electric Prod Convergence waveform-shaping circuitry
US3766429A (en) * 1971-03-12 1973-10-16 Int Standard Electric Corp Color tv focusing circuit
US3763391A (en) * 1971-12-29 1973-10-02 Gte Sylvania Inc Color television convergence apparatus
US3767962A (en) * 1972-01-03 1973-10-23 Warwick Electronics Inc Television convergence system

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4095137A (en) * 1977-03-18 1978-06-13 Sperry Rand Corporation Digital convergence system for a multi-gun crt
WO1991007047A1 (de) * 1989-11-04 1991-05-16 Deutsche Thomson-Brandt Gmbh Verfahren und vorrichtung zur bildjustierung
US5237246A (en) * 1989-11-04 1993-08-17 Deutsche Thomson-Brandt Gmbh Process and device for adjusting pictures

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Publication number Publication date
DE2321149A1 (de) 1973-11-08
NL7305846A (enrdf_load_stackoverflow) 1973-10-30
DE2321149B2 (de) 1975-07-03
JPS494918A (enrdf_load_stackoverflow) 1974-01-17

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