US3728569A - Cathode-ray tube - Google Patents

Cathode-ray tube Download PDF

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Publication number
US3728569A
US3728569A US00183586A US3728569DA US3728569A US 3728569 A US3728569 A US 3728569A US 00183586 A US00183586 A US 00183586A US 3728569D A US3728569D A US 3728569DA US 3728569 A US3728569 A US 3728569A
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United States
Prior art keywords
ray tube
gap
electron beams
convergence device
pole shoes
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Expired - Lifetime
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US00183586A
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English (en)
Inventor
J Gerritsen
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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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Publication of US3728569A publication Critical patent/US3728569A/en
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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
    • H01J29/701—Systems for correcting deviation or convergence of a plurality of beams by means of magnetic fields at least
    • H01J29/707—Arrangements intimately associated with parts of the gun and co-operating with external magnetic excitation devices

Definitions

  • Gerritsen [451 Apr. 17, 1973 41 CATHODE-RAY TUBE [75] Inventor: Jan Gerritsen, Emmasingel, Eindhoven, Netherlands [73] Assignee: U.S. Philips York, NY.
  • the tube comprises a luminescent screen and, at a short distance therefrom, a color selection electrode.
  • the electron beams are converged by means of a magnetic convergence device.
  • the part of the convergence device present inside the tube comprises for each electron beam a pair of plateshaped pole shoes.
  • Each pole shoe is provided in a cylindrical part of the convergence device through an axial gap.
  • the cylindrical part of the convergence device furthermore comprises gaps in such manner that it holds for each axial gap that no closed electric connection exists around a single gap. As a result of this the occurrence of circulating currents around the axial gaps is counteracted.
  • the invention relates to a cathode-ray tube comprising at least one electron gun for producing a number of electron beams, a luminescent screen on the gun side of which is present at a short distance from said screen a color selection electrode in the plane of which the various electron beams are converged, and a convergence device which comprises for each electron beam a pair of plate-shaped pole shoes, each pole shoe being provided in a cylindrical part of the convergence device through an axial gap, the pairs of pole shoes being screened relative to each other by radial partitions.
  • an external magnetic convergence device is present around the neck of the tube and produces magnetic fields which are guided to the electron beams by means of the internal plate-shaped pole shoes.
  • the radial partitions screen the magnetic fields relative to each other, while the cylindrical part serves inter alia to screen the electron beams from undesirable electrostatic fields, for example as a result of charging of the wall of the neck of the tube.
  • a convergence system is used which depends upon the deflection of the electron beams so that there is dynamic convergence.
  • the magnetic field of thedynamic convergence varies approximately .parabolically with time, with the line frequency as the recurrence frequency.
  • a lagging of the parabolic magnetic field occurs relative to the field produced by the external magnetic convergence device, which lagging is approximately 4 microseconds in a normal gun.
  • the field produced by the external magnetic convergence device should lead in phase relative to the .deflection. In practice, this is'realized to a certain extent by the addition of a sawtooth component to the field, but it is no exact correction for the. lagging.
  • the cylindrical part of the convergence device comprises gaps in such manner that it holds for each axial gap that no closed electric connection exists around a single such axial gap.
  • the gaps should be arranged so that the mechanical rigidity of the cylindrical part is maintained. It has been found that in addition to a decrease of the lagging, an increase of the sensitivity of the convergence device is obtained. As a result of this a better convergence of the electron beams can be realized, while the required sawtooth component need be less strong so that a simpler circuit will do and a smaller power need be supplied for the convergence device.
  • FIG. 1 is a sectional view of a cathode-ray tube
  • FIG. 2 is an elevation of the internal convergence device
  • FIG. 3 is an elevation of another internal convergence device.
  • the cathode-ray tube 1 shown in FIG. 1 comprises a system of guns 2 shown diagrammatically and comprising three guns and an internal convergence device.
  • the guns placed in a triangular arrangement each produce an electron beam; the electron beams are converged on a shadow mask 4 by a convergence device consisting of an internal convergence device belonging to the system of guns 2 and a diagrammatically shown external convergence device 3, after which the beams each impinge upon certain parts of the luminescent screen 5.
  • the scanning of the screen is effected by a diagrammatically shown deflection device 6.
  • FIG. 2 is an elevation of an internal convergence device. It consists for each electron beam of a pair of plate-shaped poleshoes l0 and 11, 12 and 13, 14 and 15. Each plate-shaped pole-shoe is provided in a cylindrical part 16 through an axial gap. The poleshoe 10 is provided through an axial gap 17, and the poleshoe 11 through another axial gap 18. The axial gaps 17 and 18 are connected by a gap 19. As a result of this it is achieved that around the single axial gap 17 no closed electric connection exists which would not be the case in the absence of the gap 19. The same applies to the single axial gap 18.
  • FIG. 3 is an elevation of another internal convergence device. It consists for each electron beam of a pair of plate-shaped poleshoes 25 and 26, 27 and 28, 29 and 30. Each plate-shaped poleshoe is provided in a cylindrical part 31 through an axial gap. The poleshoe 25 is provided through an axial gap 32 and the poleshoe 26 is provided through another axial gap 33. The axial gaps 32 and 33 open on one side into the edge of the cylindrical part 31 and are connected by the gap at this edge of the cylindrical part 31. As a result of this it is achieved that around each axial gap no closed electric connection exists while the mechanical rigidity of the cylindrical part is maintained by the material between the axial gaps and the other edge of the cylindrical part 31. Radial partitions 34, 35 and 36 screen the pairs of poleshoes relative to each other.
  • a cathode ray tube comprising:
  • said converging means comprising a tubular member including a peripheral portion and a plurality of pairs of pole shoes employed for dynamically converging said electron beams and further comprising means for screening each one of said pairs of pole shoes from others of said pairs, said peripheral portion comprising spaced axial gaps through respective ones of which said pole shoes extend into said tubular member and further comprising a part extending in the space between a pair of said pole shoes, an end of said extending part being separated by a gap from another part of said peripheral portion so as to prevent a closed electric connection around a single one of said paired pole shoes.

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  • Video Image Reproduction Devices For Color Tv Systems (AREA)
US00183586A 1970-09-17 1971-09-24 Cathode-ray tube Expired - Lifetime US3728569A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL7013722.A NL160112C (nl) 1970-09-17 1970-09-17 Kathodestraalbuis.

Publications (1)

Publication Number Publication Date
US3728569A true US3728569A (en) 1973-04-17

Family

ID=19811072

Family Applications (1)

Application Number Title Priority Date Filing Date
US00183586A Expired - Lifetime US3728569A (en) 1970-09-17 1971-09-24 Cathode-ray tube

Country Status (9)

Country Link
US (1) US3728569A (nl)
JP (1) JPS518772B1 (nl)
AU (1) AU455382B2 (nl)
BE (1) BE772641A (nl)
CA (1) CA937972A (nl)
DE (1) DE2143125C3 (nl)
FR (1) FR2107791A5 (nl)
GB (1) GB1308118A (nl)
NL (1) NL160112C (nl)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3906282A (en) * 1974-02-19 1975-09-16 Gen Electric Precision getter alignment for cathode ray tubes
US3930180A (en) * 1973-05-21 1975-12-30 Philips Corp Color cathode ray tube magnetic pole piece support structure

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE767699A (fr) * 1970-05-27 1971-10-18 G I C Ltd Systeme de securite a sac a air du type a aspiration

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3482137A (en) * 1969-01-03 1969-12-02 Kentucky Electronics Inc Pole piece mounting structure in crt convergence electrode
US3534208A (en) * 1968-05-24 1970-10-13 Gen Electric Cathode ray tube having three in-line guns and center beam convergence shield modifying center beam raster size

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3534208A (en) * 1968-05-24 1970-10-13 Gen Electric Cathode ray tube having three in-line guns and center beam convergence shield modifying center beam raster size
US3482137A (en) * 1969-01-03 1969-12-02 Kentucky Electronics Inc Pole piece mounting structure in crt convergence electrode

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3930180A (en) * 1973-05-21 1975-12-30 Philips Corp Color cathode ray tube magnetic pole piece support structure
US3906282A (en) * 1974-02-19 1975-09-16 Gen Electric Precision getter alignment for cathode ray tubes

Also Published As

Publication number Publication date
DE2143125C3 (de) 1979-09-20
AU3346971A (en) 1973-03-22
AU455382B2 (en) 1974-11-21
JPS518772B1 (nl) 1976-03-19
CA937972A (en) 1973-12-04
NL160112B (nl) 1979-04-17
NL7013722A (nl) 1972-03-21
DE2143125B2 (de) 1979-01-18
BE772641A (fr) 1972-03-15
NL160112C (nl) 1979-09-17
DE2143125A1 (de) 1972-03-23
FR2107791A5 (nl) 1972-05-05
GB1308118A (en) 1973-02-21

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