EP0317999B1 - Ferrite sheet for correcting magnetic field produced by deflection yoke - Google Patents

Ferrite sheet for correcting magnetic field produced by deflection yoke Download PDF

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Publication number
EP0317999B1
EP0317999B1 EP19880119584 EP88119584A EP0317999B1 EP 0317999 B1 EP0317999 B1 EP 0317999B1 EP 19880119584 EP19880119584 EP 19880119584 EP 88119584 A EP88119584 A EP 88119584A EP 0317999 B1 EP0317999 B1 EP 0317999B1
Authority
EP
European Patent Office
Prior art keywords
sheet
ferrite sheet
deflection yoke
ferrite
sensitive adhesive
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
Application number
EP19880119584
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0317999A2 (en
EP0317999A3 (en
Inventor
Hiroka Yamasaki
Takashi Sakauchi
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.)
Kanegafuchi Chemical Industry Co Ltd
Original Assignee
Kanegafuchi Chemical Industry Co Ltd
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 Kanegafuchi Chemical Industry Co Ltd filed Critical Kanegafuchi Chemical Industry Co Ltd
Publication of EP0317999A2 publication Critical patent/EP0317999A2/en
Publication of EP0317999A3 publication Critical patent/EP0317999A3/en
Application granted granted Critical
Publication of EP0317999B1 publication Critical patent/EP0317999B1/en
Expired legal-status Critical Current

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Classifications

    • 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
    • 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

Definitions

  • the present invention relates to a ferrite sheet stuck on a deflection yoke placed around the neck of a cathode-ray tube for use in a television receiver or a display unit to finely adjust and correct the magnetic field set up and controlled by the yoke and, more particularly, to an improvement over such a ferrite sheet.
  • a ferrite sheet for correcting the magnetic field produced by a deflection yoke has been heretofore fabricated in the manner described below.
  • a plastic such as vinyl chloride is mixed with a soft ferrite such as Ni-Zn ferrite or Mn-Zn ferrite. The mixture is then molded into a sheet to form the body of the ferrite sheet.
  • a pressure sensitive adhesive layer is formed on one surface of the body of the sheet. Then, a sheet of release paper is attached to the surface of the adhesive layer.
  • the present applicant has already filed Japanese Utility Model application No. 35078/1987 for this ferrite sheet.
  • the pressure sensitive adhesive layer formed on one surface of the body of the sheet may attack the insulating layer coated on the surface of each turn of the winding, thus impairing the insulation. It is inferred that the organic solvent contained in the pressure sensitive adhesive attacks and dissolves the insulating layer of the winding, lowering the insulation.
  • a solvent is indispensable to allow the pressure sensitive adhesive to permeate the base material. Further, the foregoing drawback becomes more conspicuous, because the solvent tends to remain in the base material.
  • the above objects are achieved by a ferrite sheet according to claim 1.
  • the pressure sensitive adhesive layer contains substantially no organic solvent. More specifically, the body of the ferrite sheet is molded and has a given size. A layer of a pressure sensitive adhesive having substantially no organic solvent is formed on one surface of the body.
  • the pressure sensitive adhesive via which the field-correcting ferrite sheet is bonded to the surface of the winding of the deflection yoke contains hardly any organic solvent or other similar substance which can attack the insulating layer of the winding. For this reason, the solvent contained in the pressure sensitive adhesive does not attack the material of the insulating layer. Hence, the insulation between the neighboring turns of the winding does not deteriorate.
  • a deflection yoke according to the invention.
  • This yoke is placed around the neck of a cathode-ray tube (not shown).
  • a sheet 3 made of a ferrite is stuck on an appropriate portion of the surface of a winding 2 to correct the magnetic field produced by the yoke 1.
  • the sheet 3 is fabricated in the manner described below.
  • a soft ferrite such as Ni-Zn ferrite or Mn-Zn ferrite is mixed with a plastic such as polyvinyl chloride.
  • the mixture is molded into a sheet, which is then cut into a desired size to form the body of the ferrite sheet.
  • a layer 4 of pressure sensitive adhesive is formed on one surface of the body.
  • the adhesive layer 4 does not contain any base material consisting of nonwoven fabric, Japanese paper, polyester film, film of foamed polyurethane but consists only of a pressure sensitive adhesive which does not substantially contain any solvent or other component that attacks insulating materials.
  • the pressure sensitive adhesive can be a known pressure sensitive adhesive made from an acrylic resin or a rubber.
  • Fig. 2 is an enlarged cross section of the winding 2 that constitutes the deflection yoke on which the field-correcting ferrite sheet is stuck.
  • the winding 2 comprises a copper wire 6, an insulating layer 5 made from a synthetic resin such as urethane resin or polyester, and a self-fusing layer 7 made of a nylon.
  • the layer 7 acts to bond together neighboring turns of the windings.
  • This field-correcting ferrite sheet fabricated in this way can be directly stuck on an appropriate portion of the surface of the deflection yoke 1.
  • a sheet of release paper can be placed on the pressure sensitive adhesive layer 4. When the ferrite sheet is used, the sheet of release paper is peeled off, and then the ferrite sheet is stuck on an appropriate portion of the surface of the deflection yoke 1.
  • the novel ferrite sheet for correcting the magnetic field does not contain any base material consisting of a sheet of nonwoven fabric, Japanese paper, fabric, or a synthetic resin. Rather, only a pressure sensitive adhesive is applied to the body of the ferrite sheet. Therefore, it is unlikely that the insulating layer 5 of the winding 2 forming the deflection yoke 1 is attacked. Consequently, the insulation between the neighboring turns of the winding 2 does not deteriorate. This completely prevents the turns of the copper wire 6 from causing short between them.
  • thickness d of the pressure sensitive adhesive layer 4 is set larger than the radius r of each turn of the winding 2.
  • the insulating performance of the novel field-correcting ferrite sheet 3 was compared with the insulating performance of a conventional field-correcting ferrite sheet including a base material of nonwoven fabric. The results are shown in the Table below.
  • a series of experiments was made as follows. As shown in Fig. 5, two windings 8 were twisted together to form a coil. Two portions of the coil were wrapped in two field-correcting ferrite sheets 9 and fixed. Simultaneously, the surfaces of the sheets were coated with acetate tape 10. This coil was placed in a constant temperature oven the inside of which was maintained at 110°C. The coil was heated for 24 hours. Then, it was taken out of the oven.
  • High voltages were applied between the windings 8 of the coil without removing the ferrite sheets 9 to perform a withstand voltage test.
  • the coil was heated by the oven to take account of the environment under which the deflection yoke is actually used.
  • the high voltages were impressed at a room temperature of 28°C at a normal pressure.
  • a 60Hz AC power supply was employed as the power source of the high voltages.
  • Experiment 1 Table insulating material Experiment 1 (no base material) Experiment 2 (with base material) Experiment 3 (no ferrite sheet) Experiment 4 (no ferrite sheet) urethane resin 13.2-14.0 KV 12.5-13.2 KV 13.8-14.5 KV 13.5-14.5 KV polyester resin 13.1-14.5 KV 10.4-12.0 KV 13.0-14.7 KV 12.5-13.0 KV Referring to the Table above, Experiment 1 was made using the novel field-correcting ferrite sheet. A pressure sensitive adhesive made of an acrylic resin was directly applied to one side of a sheet of polyvinyl chloride containing 81% by weight of a soft ferrite.
  • Experiment 2 was made using a layer of a pressure sensitive adhesive containing a base material of nonwoven fabric as the pressure sensitive adhesive layer of the aforementioned field-correcting ferrite sheet.
  • Experiments 3 and 4 were made using only coils fabricated by twisting together windings; no ferrite sheet for correcting the magnetic field was employed. Under these conditions, in Experiment 3 the coil was heated, while in Example 4 it was not heated.
  • the ferrite sheet consisting simply of the pressure sensitive adhesive sheet (Experiment 1) are quite similar in resistance to voltage to the structures having no ferrite sheet (Experiments 3 and 4).
  • the resistance to voltage of the structure having a base material of nonwoven fabric (Experiment 2) is lower. This lower resistance to voltage is estimated to be caused by the solvent contained in the nonwoven fabric. In reality, three experiments were made for each of the structures shown in the Table, and the average value was calculated and shown in the Table.
  • the novel field-correcting ferrite sheet of a deflection yoke which uses as its pressure sensitive adhesive layer a pressure sensitive adhesive layer containing substantially no organic solvent. Therefore, when this sheet is stuck on the surface of the deflection yoke, the insulating layer of the winding of the yoke is not attacked. Consequently, the yoke does not malfunction after it is used for many years.

Landscapes

  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
  • Adhesives Or Adhesive Processes (AREA)
EP19880119584 1987-11-25 1988-11-24 Ferrite sheet for correcting magnetic field produced by deflection yoke Expired EP0317999B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP179406/87 1987-11-25
JP1987179406U JPH0755810Y2 (ja) 1987-11-25 1987-11-25 偏向ヨークの磁界補正用フェライトシート

Publications (3)

Publication Number Publication Date
EP0317999A2 EP0317999A2 (en) 1989-05-31
EP0317999A3 EP0317999A3 (en) 1989-10-18
EP0317999B1 true EP0317999B1 (en) 1992-09-16

Family

ID=16065313

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19880119584 Expired EP0317999B1 (en) 1987-11-25 1988-11-24 Ferrite sheet for correcting magnetic field produced by deflection yoke

Country Status (3)

Country Link
EP (1) EP0317999B1 (enrdf_load_stackoverflow)
JP (1) JPH0755810Y2 (enrdf_load_stackoverflow)
DE (1) DE3874686T2 (enrdf_load_stackoverflow)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE1007166A3 (nl) * 1993-05-13 1995-04-11 Philips Electronics Nv Beeldbuis met afbuigeenheid.

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5820455B2 (ja) * 1977-09-21 1983-04-23 株式会社日立製作所 偏向ヨ−ク
JPS58154144A (ja) * 1982-03-10 1983-09-13 Hitachi Ltd 陰極線管の偏向ヨ−ク固定用クサビ構体
US4449109A (en) * 1982-11-08 1984-05-15 Ball Corporation Magnet support collar
JPS61114445A (ja) * 1984-11-08 1986-06-02 Sony Corp 偏向装置
JPS61162931U (enrdf_load_stackoverflow) * 1985-03-29 1986-10-08

Also Published As

Publication number Publication date
DE3874686T2 (de) 1993-04-15
JPH0183252U (enrdf_load_stackoverflow) 1989-06-02
EP0317999A2 (en) 1989-05-31
DE3874686D1 (de) 1992-10-22
JPH0755810Y2 (ja) 1995-12-20
EP0317999A3 (en) 1989-10-18

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