EP0348205A2 - Vorrichtung zum Eliminieren von magnetischen Streufeldern in Bildwiedergabeeinrichtungen - Google Patents

Vorrichtung zum Eliminieren von magnetischen Streufeldern in Bildwiedergabeeinrichtungen Download PDF

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Publication number
EP0348205A2
EP0348205A2 EP89306338A EP89306338A EP0348205A2 EP 0348205 A2 EP0348205 A2 EP 0348205A2 EP 89306338 A EP89306338 A EP 89306338A EP 89306338 A EP89306338 A EP 89306338A EP 0348205 A2 EP0348205 A2 EP 0348205A2
Authority
EP
European Patent Office
Prior art keywords
wires
crt
deflecting
flux
front surface
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
EP89306338A
Other languages
English (en)
French (fr)
Other versions
EP0348205B1 (de
EP0348205A3 (en
Inventor
Kimiteru Ono
Yoshiro Hakamada
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.)
Victor Company of Japan Ltd
Original Assignee
Victor Company of Japan 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 Victor Company of Japan Ltd filed Critical Victor Company of Japan Ltd
Publication of EP0348205A2 publication Critical patent/EP0348205A2/de
Publication of EP0348205A3 publication Critical patent/EP0348205A3/en
Application granted granted Critical
Publication of EP0348205B1 publication Critical patent/EP0348205B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • H01J29/003—Arrangements for eliminating unwanted electromagnetic effects, e.g. demagnetisation arrangements, shielding coils
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2229/00—Details of cathode ray tubes or electron beam tubes
    • H01J2229/0007—Elimination of unwanted or stray electromagnetic effects
    • H01J2229/0015—Preventing or cancelling fields leaving the enclosure

Definitions

  • the present invention relates to a device for the suppression of the leakage of magnetic flux from a display apparatus using a cathode ray tube (a CRT), and more particularly relates to a device for reducing the leakage flux from the deflecting yoke having deflecting coils in order to deflect the electron beam, and which gives an adverse influence to other apparatus in front of the display apparatus.
  • a CRT cathode ray tube
  • a display apparatus 1 having a CRT 2 uses magnetic fields occurring by coils of a deflecting yoke 3 in order to deflect the electron beam from an electron gun 4.
  • a display apparatus 1 having the above configuration has a problem that the magnetic flux leaks out of the apparatus by causing a current to flow in the coils of the yoke 3 and thereby generate a magnetic field.
  • the leakage flux occasionally gives an adverse influence to the operation of other apparatus. Furthermore, it is serious for the leakage flux to give an adverse influence not only to peripheral apparatus but also to persons in front of the display apparatus 1.
  • the object of the present invention is to provide a device for suppressing the unnecessary leakage flux from the display apparatus without obstructing the image plane of the display apparatus, so as to solve the above problems.
  • a device for the suppression of the leakage flux according to the present invention which is provided in a display apparatus for displaying images by deflecting an electron beam by magnetic field generated by a deflecting yoke, and by causing a fluorescent character display surface to emit light by the deflected electron-beam, comprises a pair of electric wires which are respectively arranged side by side at the upper and lower ends out of the effective picture area and which are connected to a deflecting yoke in parallel, and a controller for causing current flowing in the yoke to flow in the wires and for controlling the current flowing in the wires.
  • a deflecting current flows in coils of the deflecting yoke in order to deflect the electron beam in the CRT.
  • a part of the magnetic flux occurring in the deflecting yoke by the deflecting current leaks from the fluorescent character display surface of the display apparatus.
  • the wires arranged at the above position receive current supply for controlling the occurrence and quantity of the magnetic flux having a direction opposite to the leakage flux from the fluorescent character display surface. The magnetic flux occurring in the wires by the current supply cancels or negates the leakage flux from the deflecting yoke.
  • the present invention has the excellent effect that the leakage flux from the fluorescent surface can be reduced without any obstacle being disposed in front of the effective picture area of the CRT.
  • the leakage flux out of the display apparatus can be sharply reduced in all directions.
  • the present invention is effective in reducing the leakage flux to the standards of the VDE - Verband Deutscher Elektrotechniker (Union of Electric Engineers of Germany) of West Germany.
  • FIGS. 2 and 3 are perspective illustrations showing an embodiment according to the present invention.
  • a display apparatus 1 comprises a CRT 2, a deflecting yoke 3, an electron gun 4, cancelling wires 5a and 5b for generating cancellation flux to cancel leakage flux, a variable or fixed inductor 6 connected in parallel with the wires 5a and 5b, and a horizontal deflection circuit 10 for controlling the cancelling wires 5a and 5b.
  • the circuit 10 comprises an inductor 11, a battery 12, a diode 13, a capacitor 14, and a switching transistor 15.
  • the circuit 10 also has a flyback transformer for accelerating an electron beam and for obtaining a high voltage.
  • the circuit 10 is connected via the deflecting yoke 3 to a parallel circuit in which the cancelling wires 5a and 5b and the control inductor 6 are connected in parallel.
  • FIGS. 1 and 5 are schematic side views showing the CRT 2 and the leakage flux leaking from the horizontal deflecting coils.
  • FIG. 5 further shows that the cancelling wires 5a and 5b negate or reduce the leakage flux generated by current supplied to the horizontal deflecting coils.
  • the wires 5a and 5b are arranged in front of a face-­plate 2a of the CRT 2 as shown in FIG. 3.
  • the upper wire 5a is arranged horizontally at the top end of an effective picture area in the face-plate 2a along the horizontal direction.
  • the lower wire 5b is arranged horizontally at the bottom end of the effective area of picture in the face-plate 2a.
  • a conductor 5 of the cancelling wires 5a or 5b or both may be located at a position in front of a glass face plate 2a of the CRT 2 and over the CRT's own display area, i.e. the conductor 5 is located on or below a level L of a side envelope 2b of the CRT 2 in the side view, in other words over the CRT's fluorescent screen 2c, where the conductor 5 is still covered by a mask portion 20a of the cabinet 20 so that it is not visible to a viewer.
  • the level L is a line extrapolated forward from an inner surface of the side envelope 2b of the CRT 2.
  • the conductor 5 may be placed against the glass face plate 2a (see FIG. 10) or remote therefrom (see FIG. 9) by a distance d as this location is found to be more effective than the former.
  • the deflecting yoke 3 is assembled in the proximity of the electron gun 4 and deflects the electron beam generated therefrom.
  • the horizontal deflection circuit supplies the deflecting yoke 3 with current for horizontal deflection.
  • the current is the variable or fixed inductance 6 and is supplied to both the wires 5a and 5b, so that the suppression device of this invention synchronously operates with the deflecting yoke 3.
  • the leakage flux from the deflecting yoke changes according to the shape of the display apparatus and the strength of the deflecting current. Accordingly, the current flowing in the wires may be divided and supplied to the inductor 6 which is connected in parallel with wires 5a and 5b, so that it is possible to change the inductance of the circuit and to regulate the strength of cancellation flux. Since the cancellation flux is well-­balanced with the leakage flux, the leakage flux can be minimized.
  • cancelling wires 5a (5b) is disposed at position a predetermined distance d from the front surface 2a as shown in FIG. 9, the present invention is not restricted in this configuration. As shown in FIG. 10, the cancelling wire 5a (5b) may be disposed at position against the front surface 2a of the CRT 2.
  • the cancelling wires are arranged at the upper and lower ends in front of the CRT in order to receive little influence from the metal parts, so that the present invention provide the effect that the value of current flowing the wires becomes extremely small.
  • the CRT may be further covered by a shield plate 21 which extends up to front end outer rim of the side envelope of the CRT 2.
  • the shield plate 21 may cover the wires 5a and 5b as well, or may further extend beyond the front surface of the CRT 2 as shown in FIG. 8B.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Video Image Reproduction Devices For Color Tv Systems (AREA)
  • Electrodes For Cathode-Ray Tubes (AREA)
  • Details Of Television Scanning (AREA)
EP19890306338 1988-06-24 1989-06-23 Vorrichtung zum Eliminieren von magnetischen Streufeldern in Bildwiedergabeeinrichtungen Expired - Lifetime EP0348205B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP15641188A JPH027334A (ja) 1988-06-24 1988-06-24 漏れ磁束軽減装置
JP156411/88 1988-06-24

Publications (3)

Publication Number Publication Date
EP0348205A2 true EP0348205A2 (de) 1989-12-27
EP0348205A3 EP0348205A3 (en) 1990-06-13
EP0348205B1 EP0348205B1 (de) 1995-10-11

Family

ID=15627160

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19890306338 Expired - Lifetime EP0348205B1 (de) 1988-06-24 1989-06-23 Vorrichtung zum Eliminieren von magnetischen Streufeldern in Bildwiedergabeeinrichtungen

Country Status (3)

Country Link
EP (1) EP0348205B1 (de)
JP (1) JPH027334A (de)
DE (1) DE68924500T2 (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0466064A1 (de) * 1990-07-12 1992-01-15 Biomagnetic Technologies, Inc. Messung von optisch induzierten biomagnetischen Reaktionen
US5200673A (en) * 1988-10-31 1993-04-06 Victor Company Of Japan, Ltd. Method and device for suppression of leakage of magnetic flux in display apparatus
EP0547856A1 (de) * 1991-12-14 1993-06-23 Sony Corporation Feldkompensation für Kathodenstrahlröhremonitor
WO1996023315A1 (en) * 1995-01-24 1996-08-01 International Business Machines Corporation Cathode ray tube display apparatus with reduced stray magnetic fields

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100490339C (zh) 2004-12-31 2009-05-20 集嘉通讯股份有限公司 一种便携式装置及其操作方法

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5166726A (ja) * 1974-12-06 1976-06-09 Tokyo Electric Power Co Terebieizohizumiboshisochi
JPS5574046A (en) * 1978-11-30 1980-06-04 Toshiba Corp Deflecting device for cathode-ray tube
JPS6264024A (ja) * 1985-09-13 1987-03-20 Mitsubishi Electric Corp 不要輻射防止装置
SE452077C (sv) * 1986-03-04 1992-12-07 Blixt Autovision Anordning foer att reducera ooenskade laeckfaelt upptraedande framfoer katodstraaleroers bildskaerm
JP2526948B2 (ja) * 1987-12-11 1996-08-21 三菱電機株式会社 カラ―陰極線管

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5200673A (en) * 1988-10-31 1993-04-06 Victor Company Of Japan, Ltd. Method and device for suppression of leakage of magnetic flux in display apparatus
EP0466064A1 (de) * 1990-07-12 1992-01-15 Biomagnetic Technologies, Inc. Messung von optisch induzierten biomagnetischen Reaktionen
EP0547856A1 (de) * 1991-12-14 1993-06-23 Sony Corporation Feldkompensation für Kathodenstrahlröhremonitor
US5485056A (en) * 1991-12-14 1996-01-16 Sony Corporation Monitoring device
WO1996023315A1 (en) * 1995-01-24 1996-08-01 International Business Machines Corporation Cathode ray tube display apparatus with reduced stray magnetic fields
US5959392A (en) * 1995-01-24 1999-09-28 International Business Machines Corporation Cancellation coil arrangement for reducing stray magnetic field emissions from CRT displays

Also Published As

Publication number Publication date
DE68924500T2 (de) 1996-03-21
EP0348205B1 (de) 1995-10-11
EP0348205A3 (en) 1990-06-13
DE68924500D1 (de) 1995-11-16
JPH027334A (ja) 1990-01-11

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