EP0565267A1 - Abschirmanordnung für Kathodenstrahlröhre - Google Patents

Abschirmanordnung für Kathodenstrahlröhre Download PDF

Info

Publication number
EP0565267A1
EP0565267A1 EP93302219A EP93302219A EP0565267A1 EP 0565267 A1 EP0565267 A1 EP 0565267A1 EP 93302219 A EP93302219 A EP 93302219A EP 93302219 A EP93302219 A EP 93302219A EP 0565267 A1 EP0565267 A1 EP 0565267A1
Authority
EP
European Patent Office
Prior art keywords
crt
conductive
guard screen
conductive layer
deflection yoke
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.)
Granted
Application number
EP93302219A
Other languages
English (en)
French (fr)
Other versions
EP0565267B1 (de
Inventor
David Richard Birchall
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.)
Fujitsu Services Ltd
Original Assignee
Fujitsu Services 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 Fujitsu Services Ltd filed Critical Fujitsu Services Ltd
Publication of EP0565267A1 publication Critical patent/EP0565267A1/de
Application granted granted Critical
Publication of EP0565267B1 publication Critical patent/EP0565267B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/06—Screens for shielding; Masks interposed in the electron stream

Definitions

  • This invention relates to cathode ray tubes (CRTs).
  • the invention is particularly, although not exclusively, concerned with CRTs for use in monitors and display terminals for data processing apparatus.
  • Electric field emissions from a CRT comprise both DC and AC components.
  • the DC electric field generated on the surface of a CRT screen is relatively easy to reduce to acceptable levels by the incorporation of a conductive coating, available from all tube manufactures.
  • a conductive coating available from all tube manufactures.
  • 'normal' conductive coatings are high resistance and cannot cope with high levels of AC field.
  • Very low Ohmic coatings or screens are available but at high cost.
  • An object of the present invention is to provide way of reducing this AC component which does not have these problems.
  • a CRT having a deflection yoke and an internal conductive layer, characterised by a conductive guard screen between the deflection yoke and the internal conductive layer for reducing capacitative coupling between them, thereby reducing AC electric fields emitted from the viewing surface of the CRT.
  • the CRT comprises an evacuated glass envelope 10 having a cylindrical neck position 12, a flared portion 14 and a face 16.
  • An electron gun 18 is positioned in the neck 12 of the tube, and the face 16 is coated with a phosphor, in the conventional manner.
  • the envelope 10 has an internal aluminised layer 20 on its inner surface, extending from the end of the neck 12, up the flared portion 14, and over the screen 16.
  • the CRT has scan coils 22 positioned around the neck 12, for deflecting the electron beam from the electron gun 18.
  • a conductive guard screen 24 is positioned around the CRT, between the scan coils 22 and the envelope 10. This screen is connected, in use, to ground potential.
  • the guard screen 24 thus prevents or reduces the voltages induced between the coils 22 and the internal layer 20, and hence reduces AC emissions from the face 16 of the CRT. It has been found that a reduction in the order of 90-95% of the AC emissions can be achieved by use of the guard screen.
  • the guard screen 24 is formed from a flexible printed circuit, wrapped around the envelope 10.
  • the flexible printed circuit comprises a flexible insulating substrate 26, having first and second conductive patterns 28, 30 on opposite sides of the substrate.
  • the substrate 26 may comprise a polyimide film such as for example KAPTON, having a thickness of 50 microns.
  • the substrate may comprise a KAPTON base with insulating coating layers, with a total thickness of 150 microns.
  • Each of the conductive patterns comprises a set of parallel fingers, the fingers of the two patterns being interdigitated so that, the fingers of one set are positioned over the gaps between the fingers of the other set. Thus, between them, the two sets of fingers provide complete screening, without any gaps.
  • this shows a typical conductive pattern on one side of the substrate.
  • the pattern on the otherside is similar, but has its conductors offset to produce the interdigitated arrangement.
  • each pattern includes a set of parallel fingers 32, which, when the flexible printed circuit is wrapped around the CRT, form a cylindrical portion of the guard screen around the neck of the envelope.
  • Each pattern also includes two sets of concentric, arc-shaped fingers 34 which, when the guard screen is in position, form a conical portion, around the flare of the envelope.
  • the arc-shaped fingers may be replaced by radial fingers.
  • each finger preferably does not exceed approximately twice the line frequency AC signal penetration depth, otherwise the scan energy will be dissipated in heat generated from eddy current loss.
  • the finger width in millimetres may be calculated from :- Where
  • the maximum finger width lies in the range 0.5mm to 0.8mm.
  • the fingers do not have to be copper (ie standard PCB conductive coating), but could be formed in a conductive ink from a screen printing technique. Using this method a very thin, flexible guard screen could be manufactured in quantity and at competitive cost. The screen must be thin in order to fit between the scan coils and CRT neck, and flexible to form a cone around the CRT flare.
  • a further advantage of fitting a screen between the tube and scan coils is the improved immunity to the scan circuitry to tube 'flash over'. This occurs when the EHT in the tube final anode flashes across to other tube electrodes (a well known phenomenon). Capacitive coupling to the scan coils can cause failure of the electronic drive circuitry but with a screen fitted as described above, this problem would be vastly reduced.

Landscapes

  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
  • Electrodes For Cathode-Ray Tubes (AREA)
EP93302219A 1992-04-07 1993-03-23 Abschirmanordnung für Kathodenstrahlröhre Expired - Lifetime EP0565267B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9207543 1992-04-07
GB929207543A GB9207543D0 (en) 1992-04-07 1992-04-07 Cathode ray tubes

Publications (2)

Publication Number Publication Date
EP0565267A1 true EP0565267A1 (de) 1993-10-13
EP0565267B1 EP0565267B1 (de) 1996-01-03

Family

ID=10713564

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93302219A Expired - Lifetime EP0565267B1 (de) 1992-04-07 1993-03-23 Abschirmanordnung für Kathodenstrahlröhre

Country Status (7)

Country Link
EP (1) EP0565267B1 (de)
JP (1) JPH0668807A (de)
DE (1) DE69301177T2 (de)
DK (1) DK0565267T3 (de)
FI (1) FI931575A (de)
GB (1) GB9207543D0 (de)
NO (1) NO307397B1 (de)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2545120A (en) * 1948-02-27 1951-03-13 Rca Corp Cathode-ray tube arc-over preventive
FR2379906A1 (fr) * 1977-02-08 1978-09-01 Philips Nv Dispositif reproducteur d'images
US4392083A (en) * 1981-11-20 1983-07-05 Teletype Corporation Radiation shield for a cathode ray tube
GB2255441A (en) * 1991-04-18 1992-11-04 Mitsubishi Electric Corp Cathode -ray tube screening arrangement

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2545120A (en) * 1948-02-27 1951-03-13 Rca Corp Cathode-ray tube arc-over preventive
FR2379906A1 (fr) * 1977-02-08 1978-09-01 Philips Nv Dispositif reproducteur d'images
US4392083A (en) * 1981-11-20 1983-07-05 Teletype Corporation Radiation shield for a cathode ray tube
GB2255441A (en) * 1991-04-18 1992-11-04 Mitsubishi Electric Corp Cathode -ray tube screening arrangement

Also Published As

Publication number Publication date
FI931575A0 (fi) 1993-04-07
GB9207543D0 (en) 1992-05-20
DK0565267T3 (da) 1996-02-05
NO307397B1 (no) 2000-03-27
NO931045D0 (no) 1993-03-23
JPH0668807A (ja) 1994-03-11
NO931045L (no) 1993-10-08
EP0565267B1 (de) 1996-01-03
FI931575A (fi) 1993-10-08
DE69301177T2 (de) 1996-10-02
DE69301177D1 (de) 1996-02-15

Similar Documents

Publication Publication Date Title
JPS6154784A (ja) 電子ビ−ムの位置制御装置
FI70763B (fi) Baogurladdningsskydd foer katodstraoleroer
US5231332A (en) AC electric field emission suppression in CRT image displays
EP0565267A1 (de) Abschirmanordnung für Kathodenstrahlröhre
JPH0815326B2 (ja) テレビジヨン表示装置
US5107179A (en) Method and apparatus for magnetic field suppression using inductive resonant and non-resonant passive loops
KR920021001A (ko) 차폐된 음극선관
KR950008407B1 (ko) 음극선관 디스플레이 장치
EP0568783B1 (de) Kathodenstrahlröhre mit Ablenkjoch
US4188564A (en) Cathode ray tube having low resistance contact area beneath high voltage contact spring
US5841234A (en) Device for shielding electric field emitted backward from video display appliance
JP3354665B2 (ja) 画像表示装置
EP0763950A1 (de) Elektrostatische Sonde zur Erkennung von Kathodenstrahlanzeigeröhrensignalen
US6259216B1 (en) Cathode ray tube
EP1367626A2 (de) Kathodenstrahlröhre
JP3464328B2 (ja) 陰極線管および該陰極線管を用いたディスプレイ装置
KR100549831B1 (ko) 음극선관 디스플레이 장치
US6504325B1 (en) Cathode ray tube assembly including a socket with a resistor for changing dynamic focus voltage
CN1327472C (zh) 用于聚焦栅极的动态聚焦电压
EP0773670A2 (de) Ablenkschaltung mit Kompensation
EP0793252A2 (de) Ablenkvorrichtung für Kathodenstrahlröhre
KR200178716Y1 (ko) 음극선관용 유해차지 제거수단
JP2002044567A (ja) 陰極線管装置
JP3834990B2 (ja) 陰極線管表示装置
JPH08115685A (ja) 陰極線管表示装置

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19930723

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): DE DK GB SE

17Q First examination report despatched

Effective date: 19950228

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE DK GB SE

REG Reference to a national code

Ref country code: DK

Ref legal event code: T3

REF Corresponds to:

Ref document number: 69301177

Country of ref document: DE

Date of ref document: 19960215

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
REG Reference to a national code

Ref country code: GB

Ref legal event code: IF02

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DK

Payment date: 20020213

Year of fee payment: 10

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 20020218

Year of fee payment: 10

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20020221

Year of fee payment: 10

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20030324

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DK

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20030331

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20031001

EUG Se: european patent has lapsed
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20050201

Year of fee payment: 13

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20060323

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20060323