US3225271A - Deflection coil system - Google Patents

Deflection coil system Download PDF

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Publication number
US3225271A
US3225271A US292232A US29223263A US3225271A US 3225271 A US3225271 A US 3225271A US 292232 A US292232 A US 292232A US 29223263 A US29223263 A US 29223263A US 3225271 A US3225271 A US 3225271A
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Prior art keywords
deflection
core
coils
coil
winding
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Expired - Lifetime
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US292232A
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English (en)
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Kaashock Johannes
Lubben Gerrit Jan
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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
    • 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

Definitions

  • This invention relates to deflection coil systems for the deflection of an electron ray in a cathode-ray tube, comprising at least two diametrically opposite halves of a coil which are wound in a tapered manner and the extent of taper of which is indicated by an angle i which varies in the longitudinal direction of the deflection coil system and which determines a magnitude h which is given by the formula:
  • H is a constant magnetic field strength on the axis of the deflection coil system
  • H is the value in amps. per cub. meter and varies in the longitudinal direction of the deflection coil system
  • the magnitude h is positive at one end of the deflection coil system and negative at the other end thereof.
  • Such a deflection coil system is known from US. Letters Patent Nos. 2,866,125, 2,866,129, and 2,945,157, issued to J. Haantjes et al.
  • the comically-wound halves of the coil are formed as aircore coils which may be slipped round the neck of a cathode-ray tube intended for the display of color television images.
  • air-core coils demand a larger number or longer windings for building up the electromagnetic filed required for deflection of the electron ray than does a coil which is wound on a core made of magnetic material such, for example, as ferroxcube.
  • the ohmic value R of the coil thus becomes a minimum for a given inductance L, so that the losses i R, wherein i is the current traversing the coil, become minimum.
  • the use of two cores has the disadvantage, however, that a certain space has to be reserved between the cores to accommodate the coils wound around a core.
  • the deflection sensitivity is determined inter alia by the volume of the material employed for the cores. It will be evident that for a constant diameter of the circular cores, which diameter is substantially determined by the external diameter of the neck of the cathode-ray tube onto which the deflection coil system has to be slipped, and for a given angle of deflection of the electron ray the total length of the deflection coil system is greater with than without said interspace between the two cores.
  • said step is based on the recognition that, despite the use of a single core, the electromagnetic field active within the neck of the tube is not homogeneous, as could be expected, but inhomogeneous in the longitudinal direction of the deflection coil system if the halves of the coil are wound conically.
  • the structure of the assembly becomes much simpler, since instead of four coils on one core, hence in total eight coils on the two cores, for one direction of deflection it is now possible to wind one half of the coil on the cylindrical core in one continuous operation, thus rendering possible automatic winding of the two halves of the coil, which would be fairly difficult to realize with the eight individual coils.
  • each half of the coil is wound in two packages each comprising a plurality of layers, the winding plane of one turn of a layer being at an angle to the axis of the core and said angle being the same, but opposite for the two packages.
  • each layer is wound in a direction going from the said plane through the axis of the core to a plane at right angles thereto, which also passes through the said axis, the wire being led back from the last turn of a layer of a first package to the first turn of the corresponding layer of the second package, and from the last turn of this layer of the second package to the first turn of the subsequent layer of the first package, and so forth.
  • FIG. 2 shows a cathode-ray tube having a deflecting system in accordance with the invention but shown for deflection in one direction only;
  • FIG. 3a is a cross-sectional view at the area 2 1 in FIG. 1, in which, to simplify the explanation, only four turns are shown;
  • FIG. 4 shows diagrammatically in the unfolded state, a core with one half of the coil provided on it in two packages I and II, and
  • FIG. shows the core in the unfolded state to explain the method of winding by which the parasitic capacities between adjacent turns of sequential layers are maintained as favourable as possible.
  • FIG. 1a shows a cylindrical core 1 onto which one half 2 of the coil is wound.
  • This half of the coil comprises two packages I and II each built up of several layers.
  • Said figur'e also shows a system of co-ordinates comprising the axes x, y and z, the z-axis also being the axis of the tube onto which the coil system is slipped.
  • the y-axis represents, for example, the vertical direction of deflection and the x-axis the horizontal direction of deflection.
  • FIG. 2 shows a cathode ray tube having a single electron gun 26 for producing a single electron beam 27, which is deflected by means of the deflecting system in accordance with the invention and which comprises the core 1 and one half 2 of the coil wound on the core 1 for deflection in one direction.
  • the coil for deflection in the other direction is not shown and can also be wound on core 1 or can be an air coil. In the latter case coil 2 may be for deflection in the vertical and the air coil for deflection in the horizontal direction.
  • FIG. 2 there is shown a tube 25 with a single electron gun
  • the deflecting system in accordance with the invention may also be used for three gun color tube. In that case the three electron beams are deflected together by means of the single deflecting system.
  • each coil system comprises two halves of a coil, only one of which is shown in FIG. 1.
  • the second half which is wound on the other side of the core in entirely the same way as the half 2 of the coil, is shown diagrammatically in FIG.
  • lines 11 and 12 are drawn from the center of the figure to the conductors 3 and 5.
  • the center corresponds to the z-axis of the core 1, which axis coincides in the operative position with the axis of the tube onto which the deflection coil system is slipped.
  • the line 12 makes an angle P to the x-axis, so that the total angle made by the conductors 3 and 5, which belong to one half of the coil, is 2%,.
  • lines 13 and 4 are drawn from the center of the core 1 to the conductors 3 and 5.
  • H is a constant magnetic field strength on the axis (directed along the y-axis in the example of FIG. 3) and H is the value in amps. per cub. metre which varies in the longitudinal direction of the deflection coil system.
  • the magnitude It thus shows the desired variation, namely from positive to negative, as specified in said patents.
  • the halves of the coil shown in FIG. 1 have to provide for the vertical deflection and the halves of the coil with opposite taper (and hence with opposite variation of the magnitude h) have to provide for the horizontal deflection, dependent upon the tube for which the deflection coils are intended.
  • the deflection coil system shown in FIG. 1 can provide for the vertical deflection, for example in the case of an index tube in which the colour strips are positioned vertically, Whereas coils with an opposite taper provide for the horizontal deflection.
  • a preferred embodiment would be such that the coils for the vertical deflection are wound on the core 1, whereas the coils for the horizontal deflection are formed as air-core coils.
  • the core 1 then fulfils the function of a support for the two deflection coil systems, considerably decreases the number of turns required for the vertical deflection coils and also decreases, though to a lesser extent, the number of turns of the coils for the horizontal direction of deflection.
  • the taper is inverted, which implies that the vertical coils wound on the core must be manufactured in an exactly inverse manner to that shown in FIG. 1 and the taper of the horizontal coils has, of course, also to be matched correspondingly.
  • FIG. 3 shows the field lines which will occur when the conductors 3, 4, 5, 6, 7, 8, 9 and 10 are traversed by currents.
  • the conductors 3, 5, 8 and 10 are important since the conductors 4, 6, 7 and 9 fulfil the function of return conductors.
  • Crosses are drawn, for example, in the conductors 3 and 5, which indicates, as is wellknown, that the current enters in situ the plane of the drawing, whereas dots are drawn in the conductors 8 and 10, which indicates that the current leaves the plane of the drawing.
  • the magnetic fields produced by said currents thus acquire directions as indicated by the arrow points in the field lines drawn around said conductors.
  • the currents flow through the conductors 3 and 5 parallel with one another, as those in the conductors 8 and 10, but the currents in the conductors 3 and 5 are oppositely directed to those in the conductors 8 and 10.
  • the fields of parallel currents support one another whereas those of oppositely-directed currents counteract one another.
  • the conductors 3 and 5, as the con ductors S and 10, are situated close to each other at zzz so the the fields produced by the conductors 3 and 5 have a tendency to close into a single field line as indicated, for example, by the field line 18 for the conductors 3 and 5 and by the field line 19 for the conductors 8 and 10.
  • This closing into a single field line is enhanced by the material of the core 1 and if the currents flowing through the conductors 3 and 5 would not be opposite to those through the conductors 8 and 10, the field lines could close through the core and a magnetic field would not be active at all within the cylindrical core.
  • FIG. 4 shows the core 1 in the unfolded state and the conductors of the packages I and II are shown diagrammatically by lines which are at an angle to the line 24 which represents the plane passing through the axis of the core 1.
  • the lines extend in a direction B B and A A respectively, for package I and in a direction C C and D D respectively, for package II.
  • the winding process is as follows. The first layer of, for example, package I is wound starting at B and in a direction passing from B to A.
  • the wire When arrived at A the wire is led back from A to C for winding the first layer of package II in a direction passing from C to D.
  • the wire When arrived in D the wire is led back to B for winding the second layer of package I.
  • This layer is also wound in a direction passing from B to A and, when arrived again at A the wire (see the second layer in FIG. 5) is led back to C for winding the second layer of package II in a direction from C to D.
  • the wire arrives at D and in FIG. 5 the winding process is not shown further. It will be evident, however, that from D the wire may be led back to B for winding the third layer of package I, and so forth.
  • either points of support may be provided on the core at B and C so that the wires cannot shift, or a templet may be placed on the core so that the wires cannot shift away from B and C.
  • Such fixing is not necessary at B and C if the wires in situ engage one another. If the wires do not engage one another, for example, in view of a different angle I for obtaining a different variation of the magnitude H points of support must also be provided, or a trapezium-shaped templet must also be used at B and C
  • the complete coil may be baked to form a compact assembly so that, if use is made of a templet, the wires cannot shift even if the templet is removed afterwards.
  • a deflection coil having good symmetry properties may thus be obtained. Since there has always been wound in a direction from B to A, and in a direction from C to D and by throughconnecting from A to C, and from D to B, it is ensured that during operation the voltage induced in said conductors per layer from the other deflection coil has a polarity such that substantially no potential difference occurs between adjacent turns of sequential layers so that the parasitic capacities remain substantially uncharged.
  • the camparatively great difference in potential between the turns of package I at B and those of package II at C has no detrimental influence because the capacity is very low due to the comparatively large mean distance between said turns.
  • the above-described winding method affords the advantage that the voltage induced in the vertical deflection coils during the horizontal fly-back time has substantially no influence on the vertical deflection.
  • the deflection coil system described may be used not only for a colour television display tube of the indextype or of the Lawrence type, but also for a colour display tube having three electron guns as described, for example in US. Letters Patent 2,945,157.
  • the deflection coils can also successivefully be used, however, for a black-and-white display tube since in such a display tube the image faults can also be reduced to a minimum by said coils. Since a spot is thus obtained which is more or less elliptic it is possible to eliminate the line structure if the long axis of the ellipse is placed in the vertical direction. Such is the case if the taper for the vertical deflection coils varies as shown in FIG. 1 and the taper for the horizontal deflection coils varies in the opposite sense.
  • H is the magnteic field strength in the axis of the deflection coil system
  • H is the value in amperes per cubic meter of the winding
  • I is half the acute angle between said adjacently arranged coils
  • R is the mean radius of the winding in cm.
  • a deflection coil system for deflecting an electron ray about a longitudinal axis in a cathode ray tube comprising a cylindrical core of magnetic material encircling the said axis, a toroidal winding on said core comprising two winding sections spaced apart in diametrical confronting relationship, each of said sections comprising two coils adjacently arranged and having current flow in the same direction, said winding producing a deflection field having an intensity 3+4 cos 1 H R where H is the magnetic field strength in the axis of the deflection coil system, H is the value in amperes per cubic meter of the winding, I is half the acute angle between said adjacently arranged coils, and R is the mean radius of the winding in cm., the coils of each of said sections being separated by an amount increasing along the longitudinal axis in the direction of travel of the electron ray thereby to vary the said angle I in the longitudinal direction and produce variations of the said value h along the said longitudinal direction whereby h has a positive value
  • a deflection coil system for deflecting an electron ray about a longitudinal axis in a cathode ray tube comprising a cylindrical core of magnetic material encircling the said axis, a toroidal winding on said core comprising two winding sections spaced apart in diametrical confronting relationship, each of said sections comprising two coils adjacently arranged and having current flow in the same direction, said winding producing a deflection field having an intensity where H, is the magnetic field strength in the axis of the deflection coil system, H is the value in amperes per cubic -8 said adjacently arranged coils, and R is the mean radius of.
  • the coils of each of said sections being substantially in contact at the entrance end of the deflection system and being separated by a varying amount 'along the longitudinal axis towards the exit end of the deflection system thereby to vary the said angle 1 in the longitudinal direction and produce variations of the said value h along the said longitudinal direction whereby h has a positive value at the said entrance end and a negative value at the exit end.
  • a deflection coil system for deflecting an electron ray about a longitudinal axis in a cathode ray tube, comprising a cylindrical core of magnetic material encircling the said axis, a toroidal winding on said core comprising two winding sections spaced apart in diametrical confronting rela tionship, each of said sections comprising two coils adjacently arranged and having current flow in the same direction, said winding producing a deflection field having an intensity
  • H is the magnetic field strength in the axis of the deflection coil system
  • H is the value in amperes per cubic meter of the winding
  • I half the acute angle between said adjacently arranged coils
  • R is the mean radius of the winding in cm.

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US292232A 1962-07-19 1963-07-02 Deflection coil system Expired - Lifetime US3225271A (en)

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US (1) US3225271A (da)
AT (1) AT239873B (da)
BE (1) BE635103A (da)
BR (1) BR6350846D0 (da)
CH (1) CH425003A (da)
DE (1) DE1210090B (da)
DK (1) DK105287C (da)
ES (1) ES290099A1 (da)
GB (1) GB1055912A (da)
NL (1) NL113649C (da)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3748524A (en) * 1970-09-14 1973-07-24 Raytheon Co Image correlator tube with crossed field deflection

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE31399E (en) 1975-10-09 1983-09-27 General Instrument Corp. Vertical coil for a deflection yoke

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2455171A (en) * 1943-09-08 1948-11-30 Hartford Nat Bank & Trust Co System for magnetic deflection in cathode-ray tubes
US2945157A (en) * 1957-12-11 1960-07-12 Philips Corp Picture tubes for three-colour television systems comprising deflection coils
US3115544A (en) * 1956-04-25 1963-12-24 Hazeltine Research Inc Color-television receivers and deflection yokes

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2455171A (en) * 1943-09-08 1948-11-30 Hartford Nat Bank & Trust Co System for magnetic deflection in cathode-ray tubes
US3115544A (en) * 1956-04-25 1963-12-24 Hazeltine Research Inc Color-television receivers and deflection yokes
US2945157A (en) * 1957-12-11 1960-07-12 Philips Corp Picture tubes for three-colour television systems comprising deflection coils

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3748524A (en) * 1970-09-14 1973-07-24 Raytheon Co Image correlator tube with crossed field deflection

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ES290099A1 (es) 1963-10-16
BR6350846D0 (pt) 1973-09-20
BE635103A (da)
DE1210090B (de) 1966-02-03
GB1055912A (en) 1967-01-18
CH425003A (de) 1966-11-30
AT239873B (de) 1965-04-26
DK105287C (da) 1966-09-12
NL113649C (da)

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