US3824426A - Colour television display apparatus provided with a cathode-ray tube - Google Patents

Colour television display apparatus provided with a cathode-ray tube Download PDF

Info

Publication number
US3824426A
US3824426A US00296657A US29665772A US3824426A US 3824426 A US3824426 A US 3824426A US 00296657 A US00296657 A US 00296657A US 29665772 A US29665772 A US 29665772A US 3824426 A US3824426 A US 3824426A
Authority
US
United States
Prior art keywords
deflection
circuit
halves
correction
current
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
US00296657A
Other languages
English (en)
Inventor
E Rossaert
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.)
US Philips Corp
Original Assignee
US Philips Corp
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 US Philips Corp filed Critical US Philips Corp
Application granted granted Critical
Publication of US3824426A publication Critical patent/US3824426A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • H04N9/285—Arrangements for convergence or focusing using quadrupole lenses
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/70—Arrangements for deflecting ray or beam
    • H01J29/701—Systems for correcting deviation or convergence of a plurality of beams by means of magnetic fields at least
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/70—Arrangements for deflecting ray or beam
    • H01J29/72—Arrangements for deflecting ray or beam along one straight line or along two perpendicular straight lines
    • H01J29/76—Deflecting by magnetic fields only
    • H01J29/764—Deflecting by magnetic fields only using toroidal windings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2229/00—Details of cathode ray tubes or electron beam tubes
    • H01J2229/96—Circuit elements other than coils, reactors or the like, associated with the tube
    • H01J2229/964—Circuit elements other than coils, reactors or the like, associated with the tube associated with the deflection system

Definitions

  • ABSTRACT Colour television display apparatus in which for correction of isotropic astigmatism a correction current flows through the coil halves of at least one deflection coil unit, which current is substantially a square functionof at least one deflection current. As a result a correction quadripolar field is produced.
  • the correction current generator includes passive elements, namely impedances, diodes and transistors operating as switches.
  • the deflection coil halves are toroidally wound on the core.
  • the invention relates to colour television display apparatus provided with a cathode-ray tube including a display screen and a system of deflection coils comprising a magnetic core on which a first and a second deflection coil unit are provided, each unit comprising two preferably symmetrical coil halves, said system of deflection coils being slid on the neck of the cathoderay tube for deflecting in two substantially orthogonal directions at least one electron beam generated in the cathode-ray tube because a deflection current originating from a deflection current generator flows through each coil half, while for correction of the isotropic astigmatism a quadripolar field is generated approximately at the area of the deflection plane of the electron beam, the intensity of said field being substantially a square function of the instantaneous intensity of at
  • the relevant invention has for its object to provide improved and simplified apparatus in which substantially no supply power is required.
  • the apparatus according to the invention is characterized in that the correction current generator consists of passive elements, the correction. current flowing through the coil halves of at least one deflection coil unit and the deflection coil halves being toroidally wound on the core.
  • the correction current generator consists of passive elements, the deflection current must flow through these elements so that the correction current is superimposed on the deflection current.
  • FIG. 1 shows display apparatus provided with a three gun cathode-ray tube and switching means for supplying the correction current
  • FIG. 2 shows an embodiment of the said switching means
  • FIG. 3 shows characteristic curves of part of the embodiment according to FIG. 2,
  • FIGS. 4, 5, 6, 7 and 8 show further embodiments of the said switching means.
  • 1 denotes an aerial by which the colour television signal can be received.
  • This colour television signal is applied to an RF and IF amplifier 2 which am plifies the signal, detects it and subsequently applies it to a video amplifier 3.
  • This video amplifier 3 applies the actual video signal consisting of a luminance signal and colour difference signals to a first output 4.
  • These signals are processed in a matrix circuit 5 so that the three colour signals R, G and B become available at the output of this matrix circuit and are applied to the three cathodes K K and K of the cathode-ray tube 6 operating as a colour television display tube.
  • This tube 6 may be of the shadow-mask type and the colour image is displayed on its screen.
  • the synchronizing signal which is applied at one end to the line deflection generator 8 and at the other end to the field deflection generator 9, is derived from a second output 7 of video amplifier 3.
  • Two output terminals 10 and 11 of generator 8 at one end are connected to the deflection coil system 12 and an output terminal 13 at the other end is connected to the final anode of display tube 6 for the supply of the final anode voltage of approximately 25 kilovolts.
  • the output terminals 14 and 15 of field deflection generator 9 are likewise connected to deflection coil system 12 for the supply of the field deflection current.
  • the line deflection current derived from output terminals 10 and 11, combined with a deflection unit of deflection coil system 12 ensures the deflection of the electron beams generated by the three cathodes K K and K in the horizontal direction.
  • the field deflection current derived from output terminals 14 and 15, in co-operation with a further deflection unit of deflection coil system 12 ensures the deflection of the three electron beams in the vertical direction.
  • FIG. 2 shows an embodiment of arrangement 16.
  • Windings l7 and 18 are the coil halves of the first-mentioned deflection unit, i.e. for the horizontal deflection.
  • Arrangement 16 includes two impedances Z and Z each of which is arranged in series with one of the said windings.
  • Line deflection generator S applies the line deflection current i to the circuit according to FIG. 2.
  • impedance Z is to be considered as negative because the fields generated by the currents flowing in windings 17 and 18 support each other in the space within the core and therefore have opposite directions in the core. This applies to toroidally wound windings.
  • FIG. 3a shows the BH characteristic curve of the material of which this core is made in which B the magnetic induction and H is the magnetic field strength.
  • FIG. 3b shows the pH characteristic curve thereof in which p. dB/dI-I is the permeability.
  • the BH characteristic curve has a substantially square variation. It follows that the uI-I characteristic curve for the same deviation about field strengths H, and H has a substantially linear variation.
  • FIG. 4 may be used with two cores 19 and 20 whose primary windings constitute the impedances Z and Z while a direct current I flows through secondary windings 21 and 22, which current is adjustable by means of a battery 23 and a variable resistor 24.
  • FIG. 4 shows that current I provides a positive premagnetisation for one of the cores l9 and 20 and a negative premagnetisation for the other core.
  • FIG. 5 shows another embodiment of circuits l6 and 16' of FIG. 1 in which in this embodiment the vertical deflection is corrected.
  • Deflection generator 9 supplies the field deflection current i Circuit 16' includes two diodes D, and D and an impedance Z which are arranged as shown in FIG. 5.
  • the diodes are considered as ideal switches it can be assumed that one diode conducts during one half of the sweep of the sawtooth deflection current and then constitutes a short circuit while the other diode is blocked. During the other half of the sweep the reverse situation occurs. Therefore the deflection current always flows through impedance Z.
  • the deflection coil halves not only generate the deflection field but also a quadripolar field whose pole axes are located approximately in the same manner as was the case for the arrangement according to FIG. 2, provided that the deflection coils are toroidally wound and are placed symmetrically relative to the horizontal and/or vertical deflection directions.
  • the field strength thereof is proportional to the deflection current and can therefore be represented as a symmetrical triangle as a function of time, which may be considered as an approximation of a parabola.
  • coil halves 17 and 18 have an impedance Z R jwL in which R and L are the resistance and the inductive part, respectively, of impedance Z Since the proportionality constant k is a real number, impedance Z must be equal to Z R jwL with L/R z L /R while the choice of the absolute value of k depends on the desired slope of the mentioned triangular function.
  • impedance Z must be a predominantly resistive impedance. 7
  • FIG. 6 shows a refinement of the arrangement according to FIG. 5 in which diodes D and D are replaced by two transistors T and T of opposite types. These transistors do not operate as amplifiers but as switches and are either saturated or cut off while the conducting and cut-off periods are adjustable by means of two supply voltages +V and V,, and two base resistors so that their function is the same as that of diodes D and D of FIG. 5 and, likewise as these diodes, may be considered as passive elements.
  • the adjustment of transistors T and T may be such that the two transistors conduct about the centre of the sweep so that the field strength of the correction quadripolar field as a function of time is trapezoid-shaped, which is a better approximation of the desired parabola shape.
  • Transistors have the additional advantage that the voltage drop thereacross in case of saturation is lower than in diodes.
  • FIG-7 shows a modification of the apparatus according to the invention in which the deflection coil halves are arranged in series.
  • Winding 27 is a secondary winding of an output transformer associated with deflection generators 8 and 9.
  • Two preferably identical series arrangements of diodes D' and D' and of an impedance Z are arranged between the junction N of deflection coil halves 17 and 18 and 25 and 26, respectively, and two taps P and P which are located symmetrically relative to the central tap M of winding 27.
  • Diodes D' and D may be replaced bytransistors in a corresponding manner as described hereinbefore.
  • Central tap M conveys the same potential as point N so that one diode conducts while the other is blocked.
  • the current flowing through one coil half is the sum of the deflection current and a current proportional to the deflection current and that the current flowing through the other coil half is the difference between the deflection current and the same current.
  • FIG. 8 shows a complete diagram of the apparatus according to the invention in which a circuit according to that of FIG. 2 is used for the horizontal deflection and a circuit according to that of FIG. 5 is used for the vertical deflection.
  • a circuit for a system of deflection coils comprising a magnetic core, first and second deflection units, each unit comprising two coil halves toroidally wound on said core, said circuit comprising a pair of deflection current generator means for generating two substantially linear deflection currents, means coupling said generator means to said units respectively; and means for correcting isotropic astigmatism comprising means for generating a quadripolar field having an intensity that is substantially a square function of one of the deflection currents, said quadripolar generating means comprising a passive element correction current generator means, and means for coupling said passive correction means to at least one deflection coil unit for providing a correction current through the halves thereof.
  • one of said units comprises a horizontal deflection unit
  • said correction generator means comprising a pair of equal inductance saturable coils having magnetic fields of opposite directions in the absence of the horizontal deflection current, said saturable coils being series coupled to said horizontal coil halves respectively whereby series circuits are formed, said series circuits being parallel coupled together.
  • said correction generator means comprises a pair of unidirectional conducting elements series coupled to said halves of oneof said units respectively, whereby two series circuits and a pair of junctions between said elements and halves are formed respectively, said series circuits being parallel coupled together, said elements having opposite conductivity directions, and an impedance means coupled between said junctions.
  • a circuit as claimed in claim 1 wherein at least two of said halves are series coupled together, whereby a series arrangement having a junction is formed, and said correction generator means comprises a winding coupled to said series arrangement and having a pair of taps symmetrical relative to the center of said winding, a pair of series circuits each comprising of a unidirectional conducting element and an impedance means series coupled thereto, said series circuits being coupled between said junction and said taps respectively.
  • each of said elements comprises an adjustable conducting period transistor.
  • each of said elements comprises an adjustable conducting period transistor.
  • each of said coil halves have resistance and reactance and said impedance means comprises an inductor having resistance and reactance in a ratio substantially equal to the corresponding ratio in said halves.
  • a circuit as claimed in claim 3 wherein each of 9.
  • a circuit as claimed in claim 1 further comprising said coil halves having resistance and reactance and said deflection units.
  • said impedance means comprises an inductor having 10.
  • a circuit as claimed in claim 9 wherein said coil resistance and reactance in a ratio substantially equal halves are symmetrical. to the corresponding ratio in said halves.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Details Of Television Scanning (AREA)
  • Video Image Reproduction Devices For Color Tv Systems (AREA)
US00296657A 1971-10-23 1972-10-11 Colour television display apparatus provided with a cathode-ray tube Expired - Lifetime US3824426A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL7114607A NL7114607A (enrdf_load_stackoverflow) 1971-10-23 1971-10-23

Publications (1)

Publication Number Publication Date
US3824426A true US3824426A (en) 1974-07-16

Family

ID=19814322

Family Applications (1)

Application Number Title Priority Date Filing Date
US00296657A Expired - Lifetime US3824426A (en) 1971-10-23 1972-10-11 Colour television display apparatus provided with a cathode-ray tube

Country Status (7)

Country Link
US (1) US3824426A (enrdf_load_stackoverflow)
JP (1) JPS4851535A (enrdf_load_stackoverflow)
BE (1) BE790455A (enrdf_load_stackoverflow)
DE (1) DE2251019A1 (enrdf_load_stackoverflow)
FR (1) FR2156923B3 (enrdf_load_stackoverflow)
GB (1) GB1411807A (enrdf_load_stackoverflow)
NL (1) NL7114607A (enrdf_load_stackoverflow)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5515426Y2 (enrdf_load_stackoverflow) * 1973-09-19 1980-04-09
JPS5044725A (enrdf_load_stackoverflow) * 1973-12-04 1975-04-22

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2869026A (en) * 1952-01-02 1959-01-13 Du Mont Allen B Lab Inc Cathode ray sweep correction system
US2906919A (en) * 1955-12-27 1959-09-29 Gen Electric Deflection circuit
US3341735A (en) * 1964-01-31 1967-09-12 Sargent Industries Display system utilizing cathode ray tube deflection error compensating means
US3571653A (en) * 1967-08-18 1971-03-23 Motorola Inc Horizontal pincushion correction circuit
US3714500A (en) * 1969-06-27 1973-01-30 Philips Corp Color television display device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2869026A (en) * 1952-01-02 1959-01-13 Du Mont Allen B Lab Inc Cathode ray sweep correction system
US2906919A (en) * 1955-12-27 1959-09-29 Gen Electric Deflection circuit
US3341735A (en) * 1964-01-31 1967-09-12 Sargent Industries Display system utilizing cathode ray tube deflection error compensating means
US3571653A (en) * 1967-08-18 1971-03-23 Motorola Inc Horizontal pincushion correction circuit
US3714500A (en) * 1969-06-27 1973-01-30 Philips Corp Color television display device

Also Published As

Publication number Publication date
BE790455A (fr) 1973-04-24
FR2156923A1 (enrdf_load_stackoverflow) 1973-06-01
NL7114607A (enrdf_load_stackoverflow) 1973-04-25
FR2156923B3 (enrdf_load_stackoverflow) 1975-11-28
DE2251019A1 (de) 1973-04-26
JPS4851535A (enrdf_load_stackoverflow) 1973-07-19
GB1411807A (en) 1975-10-29

Similar Documents

Publication Publication Date Title
US3906305A (en) Circuit arrangement for generating a sawtooth deflection current through a line deflection coil
US3440483A (en) Color television display device
GB1190815A (en) Improved Simplified Deflection System for a Plural Beam Cathode Ray Tube
US3930185A (en) Display system with simplified convergence
US4162470A (en) Magnetizing apparatus and method for producing a statically converged cathode ray tube and product thereof
US3793554A (en) Colour television display apparatus provided with a cathode-ray tube
US3898520A (en) Deflection coils and system having two quadripolar fields at a forty five degree angle with respect to each other
US4227122A (en) Convergence device for projection type color television system
US4189659A (en) Color-television picture tube with internal permanent magnets for convergence correction
US4088930A (en) Color television display device including a cathode-ray tube
US3824426A (en) Colour television display apparatus provided with a cathode-ray tube
US3622835A (en) Current-generating circuit
US3906303A (en) Colour television display apparatus incorporating a television display tube
GB1218068A (en) Convergence system for a color picture tube
US3914652A (en) Color television display apparatus provided with a modulator for generating a correction current for correcting deflection errors
US2743381A (en) Raster centering control
US3631296A (en) Television deflection system
US3803444A (en) Television display apparatus employing convergence correction
US3441788A (en) Circuit arrangements for dynamic lateral convergence
US3717788A (en) Cathode ray tube arrangement utilizing magnetic shunts for controlling color registration
US2928981A (en) Multi-beam convergence apparatus
US4677349A (en) Self converging deflection yoke for in-line gun color CRT
US3422303A (en) Convergence circuit for television receivers
US3857057A (en) Colour television display apparatus provided with a picture display tube with electron beams generated in one plane
US3560793A (en) Color television convergence system