US3015691A - Circuit arrangement for the imagedeflection and line-deflection coils of at least two cathode-ray tubes - Google Patents

Circuit arrangement for the imagedeflection and line-deflection coils of at least two cathode-ray tubes Download PDF

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Publication number
US3015691A
US3015691A US791059A US79105959A US3015691A US 3015691 A US3015691 A US 3015691A US 791059 A US791059 A US 791059A US 79105959 A US79105959 A US 79105959A US 3015691 A US3015691 A US 3015691A
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deflection
coils
tubes
cathode
line
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Expired - Lifetime
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US791059A
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Poorter Teunis
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US Philips Corp
North American Philips Co Inc
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US Philips Corp
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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

  • This invention relates to circuit arrangements for the image-deflection and line-deflection coils of at least two cathode-ray tubes, of which a plurality of the axes are located in substantially one plane, these axes or their prolongations, intersecting at substantially one point not situated in infinity, which point is located on the optical axis of the system of cathode-ray tubes, and the deflection currents being supplied from a common source.
  • Such circuit arrangements may be used inter alia in colouror stereo-television receivers, in which the cathode-ray tubes are picture tubes and in which the images produced by them are projected on a common surface. Said arrangements may also be used in colouror stereotelevision transmitters, in which the cathode-ray tubes are camera tubes and in which the scene to be represented is projected on their photo-sensitive screens.
  • the number of the cathode-ray tubes is usually three, one of them being located in the optical axis of the system and the two other ones on each side of the optical axis.
  • stereo-television only the two tubes located outside the optical axis are usually present.
  • the projection results for the tubes located outside the optical axis are trapezoidally distorted.
  • This distortion which is naturally objectionable in all cases, may be compensated, if the plane passing through the axes of the cathode-ray tubes is parallel to the direction of the line deflection, by supplying a correcting signal, composed of a sawtooth of line frequency multiplied by a sawtooth of picture frequency, to the image-deflection coils of the tubes located outside the optical axis, and if the plane passing through the axes of the cathoderay tubes is parallel to the direction of the image deflection, by supplying a correcting signal, composed of a sawtooth of line frequency multiplied by a sawtooth of picture frequency, to the line deflection coils of the tubes located outside the optical axis.
  • the correcting signal for one of the cathode-ray tubes, located outside the optical axis is naturally required to be of opposite polarity to that for the other tube.
  • correcting signals supplied to the linerespectively image-deflection coils are constituted by parabolic currents having a recurrence frequency equal to the linerespectively picture-frequency, and which are supplied to the linerespectively image-deflection coils.
  • the invention relates to a circuit arrangement in which the deflection currents for the deflection are supplied by a common source. This affords the advantage with respect to the use of a plurality of sources that relatively independent variations in deflection currents cannot now occur.
  • An object of the invention is to provide a circuit arrangement in which the correcting signals may also be derived from a source common to the various cathode-ray tubes and in which the normal deflection currents and the 3,015,691 Patented Jan. 2, 1962 correcting signals may be supplied to the coils in a simple manner.
  • the circuit arrangement according to the invention is characterized in that the imagerespectively line-deflection coils are included in a bridge circuit in which the deflection coils of two cathode-ray tubes located outside the optical axis form parts of two interconnected branches and in which the deflection coils for any other cathode-ray tubes, which in this case are located in the plane of symmetry of the first-mentioned tubes, form parts of the diagonal having a common junction point with the said branches, further characteristics being that the source for the imagerespectively line-deflection is included in said diagonal and that the source producing the signal for correction of the distortion which is attributable to the non-parallelity of the axes of the firstmentioned cathode-ray tubes, is included in the other diagonal of the bridge circuit.
  • FIG. 1 shows the arrangement of three cathode-ray tubes to which the invention is applicable
  • FIGS. 2 and 3 show the non-corrected and the partly corrected projection results of the arrangement of FIG. 1;
  • FIGS. 4 and 5 show correcting signals
  • FIGS. 6, 7 and 8 show embodiments of the circuit arrangement according to the invention.
  • FIG. 9 shows an arrangement of four cathode-ray tubes
  • FIG. 10 shows an embodiment of a circuit arrangement according to the invention applicable thereto.
  • FIG. 1 shows the arrangement of three cathode-ray tubes
  • these tubes are picture tubes of a colour-television receiver.
  • the axes a, b and c of tubes 1, 2 and 3 are located in one plane, their prolongations intersecting at a point P on the optical axis b of the system, which is not located in infinity. It is also assumed that the plane passing through the axes a, b and c is parallel to the direction of the line deflection.
  • FIG. 2 shows the projection results of said tubes on a plane passing through P at right angles to the axis b of picture tube 2.
  • the dimensions of the image 4 projected on the plane passing through P by the picture tube 1 are larger in the right-hand part of the plane, and smaller in the left-hand part of the plane, than the corresponding dimensions of the image 5 projected on the plane passing through P by the picture tube 2, the axis of which is at right angles to said plane.
  • the dimensions of the image 6 projected on the plane passing through P by the picture tube 3 are, on the contrary, smaller in the right-hand part of the plane, and larger in the left-hand part of the plane, than the corresponding dimensions of the image 5.
  • the correcting signal By supplying a correcting signal of parabolic shape, the recurrence frequency of which is equal to the line frequency, to the line-deflection coils of tubes 1 and 3, it may be ensured that the projection results of the various tubes are of the shape shown in FIG. 3.
  • This figure shows that now the vertical edges of the images 4 and 6 coincide with those of image 5, which has remained undistorted.
  • the correcting signal is also of a value such that the linearities of the images 4' and 6' have become equal to that of picture 5.
  • the parabolic correcting signal supplied to the line-deflection coil of tube 3 has the shape shown in FIG. 4.
  • a correcting signal having the shape of the signal shown in FIG. (in which the positive ordinate means an additional deflection upwards in the image direction) must be superimposed on the normal deflection current at the image-deflection coil of tube 3 and a correcting signal of opposite polarity must be superimposed on the normal deflection current at the image-deflection coil of tube 1.
  • Such a signal may fundamentally be obtained by multiplication of a sawtooth signal having a recurrence frequency equal to the line-deflection frequency by a sawtooth signal having a recurrence frequency equal to the image-deflection frequency.
  • the cathode-ray tubes 1, 2 and 3 are picture tubes
  • the projections of the image to be reproduced on the various photo-sensitive screens have shapes similar to those of the images 4, 5 and 6 shown in FIG. 2.
  • the correcting signals thus have a shape similar to that of the signals discussed in the preceding case.
  • FIG. 6 shows a circuit diagram of a circuit according to the invention for the arrangement shown in FIG. 1, in which the normal deflection currents and the correcting deflection currents for the various cathode-ray tubes may each be derived from a single source, so that the sources react upon one another to the least possible extent, whilst nevertheless the circuit arrangement is very simple of construction.
  • FIG. 6 relates to the imagedeflection coils.
  • 11 indicates the image-deflection coil of cathode-ray tube 1
  • 22 indicates the image-deflection coil of tube 2
  • 33 indicates the image-deflection coil of tube 3.
  • the impedances of said coils are supposed to be substantially equal to one another.
  • the coils 11 and 33 constitute two interconnected branches of a bridge circuit, the other branches of which are constituted by equal impedances 7 and 8.
  • the diagonal of the bridge circuit which has a common junction point 10 with the branches including the coils 11 and 33, includes the deflection coil 22 of cathode-ray tube 2.
  • Said diagonal also includes an impedance 9 which is equal to the impedances 7 and 8, this to ensure that the deflection currents supplied by a source 30 and traversing the three deflection coils 11, 22 and 33 are relatively equal.
  • the extremities of said diagonal, the points 10 and 23, are connected to terminals 14 and 15 of the source 30, which supplies the normal image-deflection current.
  • junction points 18 and 19 which determine the second diagonal of the bridge circuit, are connected to terminals 20 and 21 of a source 31, which supplies the signal for correcting the trapezoidal distortion of the images 4' and 6' produced by the tubes .1 and 3 on the plane passing through P at right angles to the axis b and hence the signal shown in FIG. 5.
  • a source 31 which supplies the signal for correcting the trapezoidal distortion of the images 4' and 6' produced by the tubes .1 and 3 on the plane passing through P at right angles to the axis b and hence the signal shown in FIG. 5.
  • the coils 11 and 33 are assumed to be equal and the impedances 7 and 8 are chosen to be equal, it follows therefrom that the currents originating from said source and traversing the coils 11 and 33 are of equal value but of opposite polarity, whilst current originating from the last-mentioned source does not traverse the coil 22.
  • the result thereof is also that the current originating from the last-mentioned source cannot react upon the first-mentioned source. Conversely, the current supplied by the first-mentioned source does not cause any potential difference across the diagonal determined by the points 18 and 19, so that this current can neither react upon the last-mentioned source.
  • the source 30 supplies the normal line-deflection current and the source 31 supplies the parabolic signal of FIG. 4, the recurrence frequency of which is equal to the line frequency.
  • the source 30 would have to supply the normal image-deflection currents and the source 31 a parabolic signal, the shape of which is shown in FIG. 4, but the recurrence frequency of which is equal to the picture frequency, and in the case that FIG. 6 relates to the line-deflection coils, the source 30 would have to supply the normal line-deflection currents and the source 31 the signal shown in FIG. 5.
  • FIG. 6 shows one embodiment of the circuit arrangement according to the invention, in which the source for the normal imagerespectively line-deflection is connected in series with the elements included in said diagonal. Identical elements in FIGS. 6 and 7 are indicated correspondingly. The figure is self-explanatory, only it is necessary to make allowance for the fact that now in the diagonal between the points 23 and 10 the current supplied by source 30 is twice as great as that traversing the branches, and that the direction of the current in said diagonal is opposite to that traversing the branches.
  • the impedance 27 may alternatively be a deflection coil of a cathode-ray tube.
  • FIG. 8 shows in greater detail the circuit arrangement of FIG. 6, in which it is assumed that the plane passing through the axes of the tubes is parallel to the direction of the line deflection and the coils are imagedeflection coils. Identical elements in FIGS. 6 and 8 are indicated correspondingly. In series with the coils 11, 22 and 33 there are connected inductances 41, 42 and 43, which serve to control the image linearity and resistors 51, 52 and 53 which permit of controlling the image amplitude.
  • the impedances 7 and 8 of FIG. 6 are consituted in FIG. 8 by the dynamic transformer impedance of a transformer 40, as seen between points 54 and 55, the primary winding of which transformer is coupled to the terminals of source 31, and by the transformer impedance, as seen between the points 55 and 56.
  • Joints 55 and 10 are connected via a transformer 60 to the terminals of source 30.
  • the source 30 is bridged by a capacitor 29.
  • FIG. 9 shows diagrammatically the arrangement of four cathode-ray tubes 61, 62, 63, 64.
  • the plane passing through the axes of the tubes 61 and 62 is assumed to be parallel to the direction of the line deflection and the plane passing through the axes of the tubes 63 and 64 is assumed to be parallel to the direction of the image deflection.
  • the normal image-deflection current must thus be supplied to the image deflection coils of all tubes.
  • the correcting signals shown in FIG. 5 naturally with opposite polarities
  • the imagedeflection coils of tubes 63 and 64 as a superposition on the normal image deflection, parabolic signals (naturally likewise with opposite polarities) as shown in FIG. 4, having a recurrence frequency equal to the picture frequency.
  • FIG. shows a circuit arrangement according to the invention for the image-deflection coils.
  • 71, 72, 73 and 74 are the image-deflection coils of the tubes 61, 62, 63 and 64.
  • the impedances of the coils 71 and 72 constitute two interconnected branches of a bridge circuit, the other branches of which are constituted by the dynamic transformer impedances of a transformer 75, as seen between points 76 and 77, and 77 and 78, respectively.
  • the diagonal of the bridge circuit which has a common point 80 with the branches including the coils 71 and 72, includes the parallel combination of the coils 73 and 74.
  • Said coils in turn constitute the branches of a bridge circuit, the two other branches of which are constituted by the dynamic transformer impedances of a transformer 81, as seen between points 82 and 83, and 83 and 84, respectively.
  • the points 77 and 80 are connected via a transformer 85 to the terminals of a source 90, which supplies the normal image-deflection current for the coils 71, 72, 73, 74.
  • a source 90 which supplies the normal image-deflection current for the coils 71, 72, 73, 74.
  • the transformers 75 and 81 allowance must be made for the fact that the deflection currents in the coils 71, 72, 73 and 74 are substantially equal to one another. (In this case it is thus again assumed that these coils are relatively equal.)
  • additional impedances may be connected in the branches including the coils 71 and 72 and/or in the branches including the coils 73 and 74.
  • the primary winding of transformer 75 is connected to a source 91, which supplies the correcting signal for the 'coils 71 and 72 of the tubes 61 and 62, which signal thus has the shape shown in FIG. 5.
  • this correcting signal does not occur in the coils 73 and 74 of the tubes 63 and 64. It will be evident that the correcting signal traverses the coils 71 and 72 with opposite polarity.
  • the primary winding of transformer 81 is connected to a source 92 which supplies the correcting signal for the coils 73 and 74 of the tubes 63 and 64, which signal has the shape shown in FIG. 4, and the recurrence frequency of which is equal to the picture frequency.
  • a source 92 which supplies the correcting signal for the coils 73 and 74 of the tubes 63 and 64, which signal has the shape shown in FIG. 4, and the recurrence frequency of which is equal to the picture frequency.
  • said signal does not occur in the coils 71 and 72 of the tubes 61 and 62.
  • This correcting signal also traverses the coils 73 and 74 with opposite polarity.
  • the circuit arrangement as such may be completely maintained.
  • the sources 90, 91 and 92 must supply respectively the normal line-deflection currents, a parabolic signal having a recurrence frequency equal to the line frequency, and a signal as shown in FIG. 5.
  • a deflection circuit for a cathode-ray tube system of the type including a pair of cathode-ray tubes having coplanar axes intersecting at a point on the optical axis of the system, the axes of said tubes being outside of said optical axis, said circuit comprising a bridge circuit, a pair of separate deflection coil means for said tubes, said pair of deflection coil means comprising adjacent arms of said bridge circuit, a source of deflection signals for said coil means, means applying said deflection signals between diagonal junctions of said bridge circuit, a source of correction signals for correcting of distortion attributable to the non-parallel disposition of said axes, and means applying said correction signals to the remaining junctions of said bridge circuit.
  • a deflection circuit for a cathode-ray tube system of the type including first and second cathode-ray tubes having coplanar axes intersecting at a point on the optical axis of the system, the axes of said tubes being outside of said optical axis, said circuit comprising a bridge circuit, first and second deflection coils positioned to deflect the beams of said first and second cathode-ray tubes respectively, said first and second deflection coils comprising adjacent arms of said bridge circuit, first and second substantially equal impedance means comprising the remaining arms of said bridge circuit, a source of deflection signals, means applying said deflection signals between diagonal junctions of said bridge circuit, a source of correction signals for correcting distortion attributable to the non-parallel disposition of the axes of said tubes, and means applying said correction signals between the remaining junctions of said bridge circuit.
  • circuit of claim 2 comprising a transformer having a primary and first and second secondary windings, said first and second secondary windings comprising said first and second impedance means, and means applying said correction signals to said primary winding.
  • a deflection circuit for a cathode-ray tube system including four cathode-ray tubes symmetrically disposed and having axes intersecting at a common point, said circuit comprising a first bridge circuit, a separate deflection coil for deflecting the beam of each of said tubes, two of said deflection coils corresponding to two symmetrical said tubes comprising adjacent arms of said first bridge circuit, a source of deflecting signals, means applying said deflecting signals between the junction of said two deflection coils and the diagonally opposite junction of said bridge circuit, a second bridge circuit, the remaining said deflection coils comprising adjacent arms of said second bridge circuit, means applying said deflecting signals between the junction of said remaining deflection coils and the opposite junction of said second bridge circuit, first and second sources of correction signals for correcting distortion attributable to the non-parallel disposition of the axes of said tubes, and means connecting said first and second correction signal sources to the remaining junctions of said first and second bridge circuits respectively.
  • first and second transformers each having a primary winding and first and second secondary windings

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US791059A 1958-02-08 1959-02-04 Circuit arrangement for the imagedeflection and line-deflection coils of at least two cathode-ray tubes Expired - Lifetime US3015691A (en)

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US (1) US3015691A (enrdf_load_stackoverflow)
DE (1) DE1123363B (enrdf_load_stackoverflow)
FR (1) FR1220216A (enrdf_load_stackoverflow)
GB (1) GB843340A (enrdf_load_stackoverflow)
NL (2) NL224759A (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3634617A (en) * 1968-12-10 1972-01-11 Harriers Electronics Corp Facetted correction lens for minimizing keystoning of off-axis projectors
JPS50151027A (enrdf_load_stackoverflow) * 1974-05-23 1975-12-04
US4210929A (en) * 1977-08-30 1980-07-01 Sony Corporation Video projecting apparatus with raster distortion correction
US5555034A (en) * 1993-06-30 1996-09-10 Hitachi, Ltd. Projection display apparatus

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1254680B (de) * 1964-02-25 1967-11-23 Fernseh Gmbh Schaltung zur Linearisierung von Ablenkstroemen fuer Farbfernsehgeraete mit mehreren Kathodenstrahlroehren

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2654854A (en) * 1950-12-22 1953-10-06 Rca Corp Image registration in color television systems or the like
US2669900A (en) * 1949-02-01 1954-02-23 Rca Corp Optical projection and registration system
US2745005A (en) * 1952-10-31 1956-05-08 Technicolor Motion Picture Cathode ray tube scanning circuit
US2758248A (en) * 1955-02-21 1956-08-07 Gen Electric Anti-pincushion circuit
US2875273A (en) * 1956-04-25 1959-02-24 Hazeltine Research Inc Color-television projector

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2669900A (en) * 1949-02-01 1954-02-23 Rca Corp Optical projection and registration system
US2654854A (en) * 1950-12-22 1953-10-06 Rca Corp Image registration in color television systems or the like
US2745005A (en) * 1952-10-31 1956-05-08 Technicolor Motion Picture Cathode ray tube scanning circuit
US2758248A (en) * 1955-02-21 1956-08-07 Gen Electric Anti-pincushion circuit
US2875273A (en) * 1956-04-25 1959-02-24 Hazeltine Research Inc Color-television projector

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3634617A (en) * 1968-12-10 1972-01-11 Harriers Electronics Corp Facetted correction lens for minimizing keystoning of off-axis projectors
JPS50151027A (enrdf_load_stackoverflow) * 1974-05-23 1975-12-04
US4210929A (en) * 1977-08-30 1980-07-01 Sony Corporation Video projecting apparatus with raster distortion correction
US5555034A (en) * 1993-06-30 1996-09-10 Hitachi, Ltd. Projection display apparatus

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DE1123363B (de) 1962-02-08
NL224759A (enrdf_load_stackoverflow)
FR1220216A (fr) 1960-05-23
GB843340A (en) 1960-08-04
NL113246C (enrdf_load_stackoverflow)

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