US3906288A - Deflection coil system for color television - Google Patents

Deflection coil system for color television Download PDF

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Publication number
US3906288A
US3906288A US399859A US39985973A US3906288A US 3906288 A US3906288 A US 3906288A US 399859 A US399859 A US 399859A US 39985973 A US39985973 A US 39985973A US 3906288 A US3906288 A US 3906288A
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United States
Prior art keywords
coil
deflection coil
display tube
coils
deflection
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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
US399859A
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English (en)
Inventor
Jan Hendrik Duistermaat
Constantius Johannes Wal Panis
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US Philips Corp
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US Philips Corp
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Publication date
Application filed by US Philips Corp filed Critical 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
    • H01J29/762—Deflecting by magnetic fields only using saddle coils or printed windings

Definitions

  • the invention relates to a deflection coil system which is adapted to be arranged about a color television display tube at the area where a rearmost cylindrical part of said display tube which comprises electron guns changes over into a flared foremost part which is provided with a display screen.
  • the said deflection coil system comprising an upper and a lower saddle-shaped deflection coil, each of which consists of one or more conductors which extend about a window in a number of turns.
  • the said deflection coils serving for deflection in the horizontal direction of the electron beams generated in the display tube.
  • Each of these horizontal deflection coils comprises two active parts, situated on both sides of the window, where the conductors extend in the longitudinal direction of the display tube along the surface of the display tube, and a foremost and a rearmost coil head where the conductors extend substantially perpendicular to the conductors in the active parts.
  • the said coil heads having approximately the shape of a part of a flat ring which is perpendicular to the axis of the display tube, the ends of said ring being arranged at a given angle distance from each other.
  • a commonly used type of color television display tube comprises three electron guns which are arranged at the vertices of an equilateral triangle and which can emit electrons which are accelerated in the direction of a display screen which comprises a large number of phosphor dots which, when struck by electrons, luminesce in one of the colors green, red or blue.
  • the phosphor dots are grouped such that each time three dots of a different color are situated at the vertices of an equilateral triangle.
  • a shadow mask is arranged between the electron guns and the display screen, the said shadow mask being a plate with openings for intercepting electrons which travel to phosphor dots of the wrong color.
  • a convergence unit is generally arranged behind the deflection coil system on the cylindrical part of the display tube.
  • This unit comprises means for generating a constant magnetic field which corrects the direction of each of the three electron beams such that the electron beams converge in the center of the screen (i.e., without deflection taking place).
  • This convergence unit furthermore comprises means for generating magnetic fields which vary with the strength of the magnetic fields generated by the deflection coil system in order to correct also convergence errors at other locations on the display screen which appear upon deflection of the electron beam.
  • a deflection coil system having a suitable asymmetry according to the invention is characterized in that the value of the said angle distance is different for the two horizontal deflection coils.
  • FIG. 1 is a substantially simplified longitudinal sectional view of a display tube for color television about which a deflection coil system is arranged.
  • FIG. 2 is a plan view of a saddle-shaped deflection coil
  • FIG. 3 is a front view of a set of horizontal deflection coils forming part of a deflection coil system according to the invention
  • FIGS. 40 and b are landing images obtained by deflection coil systems commonly used thus far.
  • FIG. 4 shows a landing image obtained by the deflection coil system according to the invention.
  • FIG. 5 is a front view of a display screen as used in the display tube shown in FIG. 1.
  • FIG. 1 is a diagrammatic longitudinal sectional view of a color television display tube 1, comprising a rearmost cylindrical part 3 which changes over into a foremost flared part 5.
  • the cylindrical part 3 comprises three electron guns 7 which are arranged at the vertices of an equilateral triangle, only two electron guns being visible in FIG. 1.
  • the flared part 5 is bounded on the front side by a display screen 9, which is shown in front view in FIG. 5 and which is covered with a mosaic of phosphor dots, each of which luminesces, when struck by an electron beam, in one of the colors blue, green or red as is shown at an increased scale in the FIGS. 44 to c to be described hereinafter.
  • a shadow mask 11 Arranged between the display screen 9 and the electron guns 7 is a shadow mask 11 which consists of a metal plate provided with openings through which only the electrons can pass which travel from one of the electron guns to a phosphor dot of the color associated with the relevant gun.
  • a deflection coil system 13 At the area of the transition from the cylindrical part 3 to the flared part 5, a deflection coil system 13, only shown diagrammatically in FIG. 1, is arranged about the display tube 1.
  • a convergence unit 15 Arranged on the rear of the deflection coil system 13 is a convergence unit 15, again only diagrammatically shown. which comprises coils for correcting the direction of the electron beams emitted by the electron guns 7 such that the three electron beams intersect each time in one point at the area of the shadow mask 11.
  • the construction of the deflection coil system 13 is generally known and is not separately shown herein.
  • the deflection coil system comprises an annular ferromagnetic core, saddle-shaped or toroidal deflection coils for the vertical deflection of the electron beams. and saddle-shaped deflection coils for the horizontal deflection of the electron beams.
  • FIG. 2 is a plan view of one of the saddle-shaped coils for horizontal deflection.
  • This figure shows a window 17 about which turns of conductive wire extend (not separately shown).
  • two active parts 19 and 21 Arranged on both sides of the window 17 are two active parts 19 and 21 where the conductors which constitute the turns extend, after ar rangement of the coil on the display tube I, approxi mately according to the longitudinal direction of the display tube and parallel to the surface thereof, i.e., approximately from the bottom upwards in FIG. 2.
  • Ar ranged on the front of the coil is a foremost coil head 23, while a rearmost coil head 25 is arranged on the rear. In these coil heads the conductors extend substantially perpendicular to the conductors in the active parts 19, 2], ie. from left to right in FIG. 2.
  • each coil head 23, 25 has the shape of a part of a flat ring which is perpendicular to the axis of the display tube 1, the said part extending over a given angle as can be seen in the front view shown in FIG. 3.
  • This Figure shows two horizontal deflection coils, one of which (27) envelops the lower half of the display tube 1 (denoted in FlG. 3 by broken lines), while the other (29) envelops the upper half.
  • the deflection coil system l3 comprises a second coil pair which is not shown. After the deflection, each electron beam must always strike a phosphor dot of the correct color on the display screen 9. Errors may then occur, as will be described hereinafter with reference to the FIGS. 40 to 6.
  • FIGS. 4a to c shows a group of three phosphor dots 31, 33 and 35 which, when struck by an electron beam, luminesce in the colors green, red and blue, respectively.
  • the display screen 9 is completely covered with such phosphor dots.
  • FIGS. 40 to c also show the cross-sections 37, 39 and 41 of the electron beams which originate from the electron guns 7 and which strike the phosphor dots 31, 33 and 35, respectively. It will be obvious that the cross-section of each bundle must lie completely within the circumference of the associated phosphor dot. If this is not so, color defects occur in the displayed colors. Therefore, the ideal situation is that where each electron beam strike the relevant phosphor dot exactly in its center.
  • the cr0ss-section of the electron beams is chosen to be smaller than the surface of the phosphor dots, with the result, however, that each phosphor dot is struck by a smaller number of electrons which has an adverse effeet on the brightness of the image. Therefore, attempts are made to approximate the ideal situation as closely as possible. It was found that the deviations between the center of the electron beam and the centre of the phosphor dot, referred to as landing errors, are not equally large over the entire surface of the display screen 9.
  • the display screen 9, shown in front view in FIG. 5, can be divided into four quadrants by a horizontal axis 43 and a vertical axis 45. It appears that the largest landing errors occur near the ends of the horizontal axis 43, i.e., in the areas denoted by 47.
  • FIGS. 41: to c relate to these areas. It was found that the landing errors in the areas 47 can be influenced by variation of the angle distance a between the ends of the foremost coil heads 23 of the horizontal deflection coils 27 and 29.
  • FIG. 4a shows the landing image which appears if the two angles are substantially equal to 180. It is obvious that in that case the cross-section of each of the three electron beams 37, 39 and 4! lies barely within the circumference of the associated phosphor dot 31, 33 and 35, respectively. A small variation in one of the many parameters determining the path of the electrons can then already exert an adverse effect on the color purity of the image,
  • a deflection coil system which is adapted to be arranged about a color television display tube at the area where a rearmost cylindrical part of said display tube which comprises electron guns, changes over into a flared foremost part which is provided with a display screen, the said deflection coil system comprising an upper and a lower saddle-shaped horizontal deflection coil.
  • each coil comprising at least one conductor which extends about a window in a plurality of turns
  • each of the horizontal deflection coils comprising two active parts situated on both sides of the window where the conductors extend in the longitudinal direction of the display tube along the surface of the display tube, and a foremost and a rearmost coil head where the conductors extend substantially perpendicular to the conductors in the active parts
  • the said coil heads having ap proximately the shape of a part of a flat ring which is perpendicular to the axis of the display tube, the ends of said ring being arranged at a given angle distance from each other, and means for correcting landing er- S 6 rors comprising the value of the said angle distance at 2.

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  • Video Image Reproduction Devices For Color Tv Systems (AREA)
US399859A 1972-10-06 1973-09-24 Deflection coil system for color television Expired - Lifetime US3906288A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL7213541A NL7213541A (enrdf_load_stackoverflow) 1972-10-06 1972-10-06

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US3906288A true US3906288A (en) 1975-09-16

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US399859A Expired - Lifetime US3906288A (en) 1972-10-06 1973-09-24 Deflection coil system for color television

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US (1) US3906288A (enrdf_load_stackoverflow)
JP (1) JPS4974424A (enrdf_load_stackoverflow)
AU (1) AU474968B2 (enrdf_load_stackoverflow)
CA (1) CA984890A (enrdf_load_stackoverflow)
DE (1) DE2346854C3 (enrdf_load_stackoverflow)
ES (1) ES419325A1 (enrdf_load_stackoverflow)
FR (1) FR2202363B1 (enrdf_load_stackoverflow)
GB (1) GB1395309A (enrdf_load_stackoverflow)
IT (1) IT995573B (enrdf_load_stackoverflow)
NL (1) NL7213541A (enrdf_load_stackoverflow)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5885258A (ja) * 1981-11-14 1983-05-21 Hitachi Ltd 投写管の偏向ヨ−ク

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2616056A (en) * 1951-02-09 1952-10-28 Sylvania Electric Prod Unsymmetrical deflection yoke
US2850678A (en) * 1955-05-03 1958-09-02 Motorola Inc Color television receiver
US3165677A (en) * 1960-08-30 1965-01-12 Gen Instrument Corp Television tube deflection coil assembly with separable yoke sections
US3195025A (en) * 1956-04-25 1965-07-13 Hazeltine Research Inc Magnetic deflection yoke
US3714500A (en) * 1969-06-27 1973-01-30 Philips Corp Color television display device

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4714739U (enrdf_load_stackoverflow) * 1971-03-18 1972-10-20

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2616056A (en) * 1951-02-09 1952-10-28 Sylvania Electric Prod Unsymmetrical deflection yoke
US2850678A (en) * 1955-05-03 1958-09-02 Motorola Inc Color television receiver
US3195025A (en) * 1956-04-25 1965-07-13 Hazeltine Research Inc Magnetic deflection yoke
US3165677A (en) * 1960-08-30 1965-01-12 Gen Instrument Corp Television tube deflection coil assembly with separable yoke sections
US3714500A (en) * 1969-06-27 1973-01-30 Philips Corp Color television display device

Also Published As

Publication number Publication date
GB1395309A (en) 1975-05-21
AU474968B2 (en) 1976-08-05
CA984890A (en) 1976-03-02
ES419325A1 (es) 1976-02-16
DE2346854A1 (de) 1974-04-11
FR2202363B1 (enrdf_load_stackoverflow) 1976-10-01
DE2346854C3 (de) 1980-09-25
AU6099573A (en) 1975-04-10
NL7213541A (enrdf_load_stackoverflow) 1974-04-09
FR2202363A1 (enrdf_load_stackoverflow) 1974-05-03
JPS4974424A (enrdf_load_stackoverflow) 1974-07-18
IT995573B (it) 1975-11-20
DE2346854B2 (de) 1980-01-31

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