EP0371618B1 - Method and device for suppression of leakage of magnetic flux in display apparatus - Google Patents

Method and device for suppression of leakage of magnetic flux in display apparatus Download PDF

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Publication number
EP0371618B1
EP0371618B1 EP89311241A EP89311241A EP0371618B1 EP 0371618 B1 EP0371618 B1 EP 0371618B1 EP 89311241 A EP89311241 A EP 89311241A EP 89311241 A EP89311241 A EP 89311241A EP 0371618 B1 EP0371618 B1 EP 0371618B1
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EP
European Patent Office
Prior art keywords
cathode ray
ray tube
magnetic flux
leakage
magnetic field
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 - Lifetime
Application number
EP89311241A
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German (de)
English (en)
French (fr)
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EP0371618A1 (en
Inventor
Hideo Hishiki
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Victor Company of Japan Ltd
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Victor Company of Japan Ltd
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Publication of EP0371618A1 publication Critical patent/EP0371618A1/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
    • 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
    • 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
    • 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
    • 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
    • H01J2229/0046—Preventing or cancelling fields within the enclosure
    • H01J2229/0053—Demagnetisation

Definitions

  • This invention relates to a method and a device for suppression of leakage of magnetic flux in a cathode ray tube display apparatus, which is adapted to suppress leakage magnetic flux generated from the deflection yoke.
  • T represents Tesla which is the unit of the strength of a magnetic field
  • the change rate of a maximum magnetic field in all relevant positions with respect to the display apparatus satisfies the requirement to be lower than 25 mT/sec.
  • display manufacturers and sellers e.g., IBM, etc.
  • the change rate of the maximum magnetic field should be lower than 15mT/sec as the standard requirement in the state of the cathode ray tube to which the deflection yoke is attached.
  • the cathode ray tube display apparatus in what is called an ITC (Integrated Tube Component).
  • the first prior art is the technology shown in Figs. 1A to 1C. This has been already filed at the Japanese Patent Office by N.V. Philips Gloellampenfabrieken (Japanese Patent Application Laid Open no. 223952/1987).
  • Figs. 1A to 1C show examples where an electric wire 1 is electrically coupled to the deflection unit and the electric wire 1 is disposed on a face-plate 2.
  • reference numerals 3a and 3b represent ordinary connection terminals of the deflection unit.
  • the electric wire 1 is connected in series with deflection coils 4a and 4b, and two horizontal sections 1a and 1b of the electric wire are directly attached to the upper and lower side edge portions of the face-plate 2, or are attached in a manner that they are extremely close thereto.
  • deflection coil 4a is coupled in series with the upper side electric wire horizontal section la and deflection coil 4b is coupled in series with the lower side electric wire horizontal section 1b.
  • a control current source 5 is disposed between the deflection coils 4a and 4b and the electric wire sections 1a and 1b.
  • the electric wire sections are wound a plurality of times, i.e., as a plurality of loops at the upper and lower side edge portions of the face-plate 2.
  • FIG. 2 (system IV) is as follows.
  • reference numeral 6 represents a cathode ray tube
  • reference numeral 7 a deflection coil
  • reference numerals 8a and 8b electric wires for producing cancellation magnetic flux, respectively.
  • the electric wires 8a and 8b are positioned around the upper and lower halves of the display surface 10, respectively.
  • a horizontal deflection current is delivered in a direction indicated by an arrow in the figure.
  • the deflection coil 7 is provided in the vicinity of an electron gun 9 so that it deflects an electron beam.
  • a horizontal deflection current is delivered from the deflection circuit to the deflection coil 7.
  • this signal is also delivered to the electric wires 8a and 8b, and varies in synchronism with the signal flowing in the deflection coil 7.
  • the leakage magnetic flux was measured under the following condition in connection with the systems I to IV according to the above-described first and second prior arts.
  • a meter capable of measuring a low frequency leakage magnetic field developed by Combinova Company in Sweden.
  • An actual measurement was conducted as follows. Antennas capable of measuring magnetic fields were installed at positions A, C and E shown in Fig. 3. The CRT display apparatus was then rotated clockwise and anticlockwise using the central point of the display apparatus as a center. The change rate of the magnetic field and the strength of the magnetic field under the condition in Figs.
  • A0, A1, A2, A14, A15, C0, C1, C2, C14, C15, E0, E1, E2, E14, E15 are measured by allowing a sawtooth current 7.8 A p-p having a horizontal deflection frequency of 20 KHz to flow in a horizontal deflection coil (not shown) of the deflection yoke 12 of the cathode ray tube 11, and by allowing a sawtooth current having a vertical deflection frequency of 60 Hz to flow in a vertical deflection coil (not shown).
  • the two electric wire sections la and 1b for cancellation of leakage magnetic flux along the upper and lower side edge portions of the face-plate 2 are connected by electric wires indicated by broken lines, which are positioned on the diagonal of the display apparatus.
  • Magnetic flux in the same direction as that of magnetic flux (leakage flux) produced by the deflection coils 4a, 4b is produced by the electric wire on the diagonal. This reduces the leakage magnetic flux cancellation effect by the electric wire sections la and 1b, and also this arrangement would not be expected to exhibit the leakage.
  • Magnetic flux cancellation effect uniformly on the above-described spherical body designated by the SSI institution.
  • the source from which a leakage magnetic flux is produced in front of the display surface of the cathode ray tube is a bent-up portion of the horizontal deflection coil.
  • a leakage magnetic flux B 2c in the same direction as that of the main magnetic flux B 2a component is produced also from the side surface portions of the cathode ray tube or the side surface portions of the deflection yoke. Since this leakage magnetic flux B 2c exerts an effect also in the forward direction of the display surface, unless such leakage magnetic flux B 2c is suppressed together with the other leakage magnetic flux, the leakage magnetic flux of the entirety of the cathode ray tube display apparatus cannot be reduced to a low level. In particular, suppression of the leakage magnetic flux B 2c toward the side surfaces was not envisaged by the prior art.
  • none of the above-described prior arts are capable of reducing the strength of an unnecessary magnetic flux over the entire periphery of the cathode ray tube, or producing apparatus which can satisfy the standard requirement of recent display manufacturers and sellers.
  • it is still necessary to reduce efficiently the leakage magnetic flux radiated from cathode ray tube display apparatus and to cause the value of the leakage magnetic flux to fall within the above-mentioned recommend limit.
  • This invention has been made in view of the above, and its object is to provide a method and a device for suppression of leakage of magnetic flux in a cathode ray tube display apparatus, which can satisfy the standard requirements of display manufacturers and sellers.
  • the object of this invention is to provide a method and a device for suppression of leakage of magnetic flux, in which magnetic flux produced from a coil for suppression of leakage of magnetic flux actually suppresses rather than reinforces leakage magnetic flux in a specific direction around CRT, and which is capable of reducing, efficiently and to such an extent as to have no serious harmful influence on the human body, a leakage magnetic flux produced from CRT, having a bad influence on other equipment and being harmful to the human body.
  • the present invention provides a device for suppression of leakage of magnetic flux in a cathode ray tube display apparatus which comprises at least a cathode ray tube having a face plate and horizontal beam deflection means which generates said leakage, said deflection means comprising a first coil having a bent-up portion and a second coil having a bent-down portion, producing a main magnetic field, which deflects an electron beam of the cathode ray tube, and a leakage magnetic field having, at the boundary between the main magnetic field and the leakage magnetic field, a direction component opposite to a parallel direction component in the main magnetic field wherein two parts of said boundary are formed at said first and second deflection coils, respectively, said device comprising:
  • the present invention also provides a device for suppression of leakage of magnetic flux in a cathode ray tube display apparatus which comprises at least a cathode ray tube having a face plate and horizontal beam deflection means which generates said leakage, said deflection means comprising a first coil having a bent-up portion and a second coil having a bent-down portion, producing a main magnetic field, which deflects an electron beam of the cathode ray tube, and a leakage magnetic field having, at the boundary between the main magnetic field and the leakage magnetic field, a direction component opposite to a parallel direction component in the main magnetic field wherein two parts of said boundary are formed at said first and second deflection coils, respectively, said device comprising:
  • electric wires and lead portions contiguous thereto for generating magnetic flux for suppression of leakage magnetic flux from the deflection coil are arranged on the upper and lower surface, and left and right side surface of the face-plate near the fluorescent display screen surface of the cathode ray tube, the side wall of the cathode ray tube, and the side surfaces of the deflection yoke, thus allowing a current in the same direction as that of a current flowing in the horizontal deflection coil to flow in the electric wires and the lead portions.
  • the strength and the change rate of a magnetic flux from the side surface of the cathode ray tube and/or the fluorescent display screen surface are reduced to a great extent all round the cathode ray tube display apparatus. Further, interference with other equipment and/or harmful influence on the human body is reduced.
  • the electric wire for suppressing a leakage magnetic flux on the demagnetization coil as in some preferred embodiments, labour used in attaching an electric wire separate from the demagnetization coil is saved, and positioning for such an attachment work or fixing of the electric wire is facilitated.
  • Fig. 6 showing the state where the device of the first embodiment is attached to a cathode ray tube display apparatus.
  • the outline of the cathode ray tube display apparatus A is composed of a cathode ray tube 53 including a fluorescent display screen surface 53a, a funnelled portion 53c, a neck portion 53d, and a side wall 56, and a deflection yoke 54 having a horizontal deflection coil (not shown) attached to the neck portion 53d.
  • electric wires 51a, 51b and four lead portions 51 a1 , 51 a1 , 51 b1 , 51 b1 contiguous thereto for producing a magnetic flux for suppressing a leakage magnetic flux are attached to the side wall 56 of the cathode ray tube 53 and the upper and lower side edge portions 53 b3 , 53 b4 of the plate portion 53 b .
  • the ends of both 51 a1 and 51 b1 are connected to connection portions 60, 60 of the deflection yoke 54 and extend in the vicinity of the side walls 56, 56.
  • FIG. 6 four metal fittings 53 f1 , 53 f4 , 53 f3 and 53 f2 are affixed on four corner portions 53 b5 , 53 b6 , 53 b7 and 53 b8 of the face-plate portion 53 b of the cathode ray tube 53, respectively.
  • electric wires 51a and 51b are arranged in the vicinity of the fluorescent display screen surface 53a along the upper and lower side edge portions 53 b3 and 53 b4 of the face-plate portion 53b from the vicinity of the metal fittings 53 f1 and 53 f4 on one side surface portion 53 b1 side of the face-plate portion 53b to the vicinity of the metal fittings 53 f2 and 53 f3 on the other side surface portion 53 b2 side, and are bent thereat.
  • a pair of electric wires 51a and 51b are disposed approximately along top and bottom rims of the face-plate portion 53b and are contiguous with lead portions 51 a1 and 51 b1 which extend to terminal portion 60 which is located at a rear of the deflection yoke 54 and on a horizontal plane which is approximately perpendicular to the face-plate portion 53b and crosses horizontally the face-plate portion 53b at its centre thereof, so that lead portions 51 a1 and 51 b1 progressively approach the horizontal plane toward the rear of the deflection yoke 54 along the side walls 56 and 56 of the funnel portions 53c.
  • the lead portions 51 a1 and 51 b1 are bent along respective side rims of the face-plate portion 53b to couple with main portions of the electric wires 5la and 51b, which are located respectively at the top and bottom rims of the face-plate portion 53b as described above.
  • Electric wires 51a and 51b may be made contiguous with the four lead wires 51 a1 , 51 b1 and 51 a1 , 51 b1 , or alternatively electric wires 51a and 51b may be made longer by the length of the lead wires in place of using these lead wires if desired.
  • Fig. 7A to 7D are circuit diagrams showing possible connections between horizontal deflection coils 50a, 50b and electric wire portions 51a, 51b for producing a magnetic flux for suppressing a leakage magnetic flux.
  • Fig. 7A the above-mentioned electric wire portions 51a, 51b connected in parallel are connected in series to the horizontal deflection coils 50a, 50b in parallel within the deflection yoke 54.
  • the connections shown in Figs. 7B to 7D, which will be described later, may be employed.
  • a variable or fixed inductance L is connected in parallel with the electric wire portions 51a, 51b connected in parallel.
  • variable resistance R is connected thereto in place of the variable or fixed inductance L shown in Fig. 7B.
  • electric wire portions 51a, 51b are connected in series to the horizontal deflection coils 50a, 50b which are connected in parallel.
  • a current approximately proportional to the deflection current flowing through the horizontal deflection coils 50a and 50b flows through the electric wires 51a and 51b.
  • the horizontal deflection coils 50a and 50b may be connected to each other in series to obtain the same effect.
  • a main magnetic flux (main deflection magnetic flux) B 2a is produced by the horizontal deflection coils 50a, 50b, a partial magnetic flux B 2b of the main magnetic flux B 2a leaks out toward the outside from the fluorescent display screen surface 53a.
  • Electric wires 51a, 51b are arranged in the vicinity of the two boundaries 55a and 55b and at the upper and lower side edge portions 53 b3 , 53 b4 of the face-plate portion 53b as close as possible to the fluorescent display screen surface 53a, respectively.
  • currents I 51a , I 51b are caused to flow in these electric wires in directions shown in Figs. 8 and 9, respectively, magnetic flux B 3a , B 3b are thereby generated.
  • These magnetic flux B 3a , B 3b act to reduce leakage magnetic flux B 1 , B 2b outside the boundaries 55a, 55b and forward of the fluorescent display screen surface 53a.
  • leakage magnetic flux B 2b radiated from the fluorescent display screen surface 53a toward the outside, and leakage magnetic flux B 1 radiated from the upper and lower side edge portions 53 b3 , 53 b4 of the face-plate portion 53b and the upper and lower sides of the funnelled portion 53c toward the outside is suppressed.
  • Leakage magnetic flux B 2c which is associated with the main magnetic flux B 2a , is produced on the side wall 56 (x-axis plane) of the cathode ray tube 53 as shown by slanting lines in the rear perspective view of a cathode ray tube display apparatus shown in Fig. 13, i.e., between the corner portion 53 b5 and the corner portion 53 b6 of the face-plate portion between which the horizontal plane is present and between the corner portion 53 b7 and the corner portion 53 b8 thereof as shown in Figs. 9 and 10.
  • the boundary between the leakage magnetic flux B 1 and the leakage magnetic flux B 2c exists substantially along the positions indicated by broken lines 57a, 57b shown in Fig. 13, i.e., four corner portions of the cathode ray tube 53 (i.e., four corner portions 53 b5 , 53 b6 , 53 b7 , 53 b8 of the face-plate portion 53b).
  • four lead portions 51 a1 , 51 b1 , 51 a1 , 51 b1 of the electric wires 51a, 51b are arranged such that the spacing ⁇ between respective lead wires gradually increases up and down from the horizontal plane as the distance between the left and right side surface portions 53 b1 , 53 b2 of the face-plate portion 53b close to the fluorescent display screen surface 53a of the cathode ray tube 53 and the deflection yoke 54 decreases.
  • a magnetic flux B 3 is produced which acts to reduce the magnetic flux B 2c .
  • leakage flux B 2c radiated from the side surface portions of the deflection yoke 54 and/or the side wall 56 of the cathode ray tube 53 can be suppressed.
  • the spacing ⁇ in Fig. 6 between lead portions 51 a1 and 51 b1 arranged at positions spaced from the side walls 56 of the cathode ray tube 53 at a predetermined interval is made too great the leakage magnetic flux B 2c becomes smaller than the cancellation magnetic flux B 3 .
  • the cancellation magnetic flux B 3 has an effect on the upper and lower portions of the boundaries 57a, 57b between the leakage magnetic flux B 2c and the leakage magnetic flux B 1 , thus to strengthen the leakage magnetic flux at the upper and lower portions of the boundaries 57a, 57b.
  • electric wires 51a, 51b and four lead portions 51 a1 , 51 b1 , 51 a1 , 51 b1 are positioned such that they pass from the side surface portion (near the horizontal plane) on the neck portion 54d side of the deflection yoke 54 through the corner portions 53 a1 to 53 a4 of the fluorescent display screen surface 53a of the cathode ray tube 53, i.e., the portions in the vicinity of the side surface portions 56, 56 of the four metal fittings 53 f1 , 53 f4 , 53 f3 , 53 f2 provided on the four corner portions 53 b5 , 53 b6 , 53 b7 , 53 b8 , of the face plate 53b.
  • lead portions 51 a1 , 51 b2 are located at positions closer to the horizontal plane than the boundary lines 57a, 57b.
  • leakage magnetic flux b 2c can be effectively suppressed, resulting in an improved leakage magnetic flux suppression effect.
  • the horizontal deflection coils 50a, 50b swing an electron beam (not shown) in a lateral direction of the cathode ray tube 53 as shown in fig. 9, a main magnetic flux B 2a is generated in a longitudinal direction perpendicular to the scanning direction (horizontal plane direction) of the electron beam.
  • horizontal deflection coils 50a, 50b are provided at the upper and lower positions on the horizontal plane of the cathode ray tube 53. Accordingly, the horizontal deflection coils 50a, 50b interchangeably produce, as magnetic flux B 1 , B 1a , B 2b produced therefrom, magnetic flux having directions opposite to the direction indicated by respective arrows shown in figs 10 and 11 in correspondence with the horizontal deflection frequency.
  • the boundary is the surface at which the magnetic flux or field changes direction or diverges.
  • the suppression means comprising the conductor means having a main portion and lead portion, is positioned at the boundary, especially at a position near the screen surface, when the suppressing magnetic field is generated, there are many suppression components between the suppressing magnetic field and the leakage magnetic field components leaked from the CRT (deflection means) and there is only a very small component of the suppressing field when reinforces the leakage field which is generated in the CRT. This arrangement therefore maximizes the suppression effect between the suppressing magnetic field generated by the suppression means (conductor means) and the leakage magnetic field from the CRT.
  • the place where two electric wires 51a, 51b and four lead portions 51 a1 , 51 b1 , 51 a1 , 51 b1 are attached is not limited to the cathode ray tube in this invention, but a leakage magnetic flux suppression device according to this invention may be attached to a structure in the vicinity of the display screen surface 53a of the cathode ray tube 53, such as a cabinet for accommodating the cathode ray tube 53 so that a predetermined leakage magnetic flux suppression effect is provided.
  • the object to which or place where the device according to this invention is attached is not limited.
  • the conductor generating the field for suppressing the leakage magnetic field is advantageously positioned at the front surface of the monitor set, this position being most distant from the source of the leakage flux (deflection means), or at the screen surface of the CRT. That is, if the suppression magnetic field is generated near the position where the leakage magnetic field is desired to be reduced (in particular where the leakage field can be reduced by a small suppression magnetic field), at the screen surface of CRT, the attenuation of the suppression magnetic field is minimized, and it is possible to use a relatively low power suppressing magnetic field to reduce the leakage magnetic flux.
  • the second embodiment of the device according to this invention has substantially the same structure as the first embodiment shown in fig. 6, but differs from the first embodiment in the following points.
  • lead portions 51 a1 , 51 b1 contiguous with electric portions 5la, 51b respectively, are arranged on the side walls 56, 56 of the cathode ray tube 53, and extend toward the side surface portion 54a and the deflection yoke 54, from intermediate positions on the side surface portions 53 b1 53 b2 of the face-plate 53b. In fig. 14 these intermediate position are approximately one quarter of the length of the side of the face plate from the respective corners. Further, these lead portions 51 a1 , 51 b1 are arranged such that the spacing ⁇ between lead portions 51 a1 and 51 b1 gradually becomes narrow as illustrated.
  • Lead portions 51 a1 , 51 b1 extending to terminal portions 60, 60 of the deflection yoke 54 are arranged adjacent and parallel to each other from a position approximately mid-way along their length to the terminal portions 60, 60 of the deflection yoke 54.
  • the third embodiment of the device according to this invention has substantially the same structure as that of the above-described first embodiment shown in fig 6, but differs from the first embodiment in the following point.
  • the device according to the third embodiment is characterized in that lead portions 51 a1 , 51 b1 contiguous to electric portions 5la, 51b are positioned on the side surface portion 56 of the cathode ray tube 53 adjacent to each other for the full length from deflection yoke 54 to a position close to the fluorescent display screen surface 53a.
  • a demagnetizing coil is positioned around the CRT to prevent the shadow mask of the CRT from being magnetised by the earth's magnetism.
  • the above-mentioned leakage flux suppression wiring may utilize the demagnetizing coil as a support.
  • Fig. 16 is a perspective view showing the state where the device according to this invention shown in fig. 18 which will be described later is attached to a cathode ray tube display apparatus
  • fig. 17 is a perspective view showing the state where the device according to this invention shown in fig. 19 which will be described later is attached to a cathode ray tube display apparatus.
  • the same components as those described above are designated by the same reference numerals, respectively and their explanation will be omitted.
  • the cathode ray tube display apparatus B has a demagnetization coil 62, which will be described later, additionally provided which is not present in the arrangement of the above-described cathode ray tube display apparatus A .
  • electric portions 51a, 51b for producing a magnetic flux for suppressing the above-described leakage magnetic flux are attached, with a predetermined spacing therebetween, to the demagnetization coil 61 for demagnetizing magnetization, etc of the shadow mask portion 53a attached on the funnelled portion 53c.
  • electric portions 51a, 51b extend along the left and right side surface portions 53 b1 , 53 b2 of the face-plate portion 53b close to the fluorescent display screen surface 53a of the cathode ray tube 53, respectively.
  • lead portions 51 a1 , 51 b1 , 51 a1 , 51 b1 contiguous thereto are conducted to the side surfaces 54a, 54a of the deflection yoke 54 substantially along a horizontal plane in the vicinity of the side walls 56, 56 of the cathode ray tube 53, and are fixed at ( predetermined positions (e.g., terminal portions 60, 60).
  • a current is caused to flow in these lead wires in a direction shown in fig. 10, thus generating a magnetic flux B 3 in a direction to reduce the magnetic flux B 2c .
  • leakage magnetic flux B 2c which leaks out from the side walls 56, 56 of the cathode ray tube 53 and the side surfaces 54a, 54a of the deflection yoke 54 can be suppressed.
  • electric portions 51a, 51b are arranged on the upper and lower side edge portion 53 b3 , 53 b4 of the face-plate 53b of the above-described cathode ray tube 53 as shown fig. 8. A current is caused to flow in these electric wires in a direction shown in fig. 8, to produce a magnetic flux B 3 for reducing the leakage magnetic flux B 2b , B 1 .
  • leakage magnetic flux B 2b , B 1 radiated from the fluorescent display screen surface 53a can be suppressed.
  • Reference numeral 61a denotes a connection appliance provided on the lead wire end of the demagnetization coil 61.
  • Reference numerals 51, 51' denote connectors attached to the initial ends 51 c1 , 51 c2 and the terminating ends 51 d1 , 51 d2 of the electric portions 51a, 51b, respectively. In place of using these connectors 51, 51', such electric wires may be soldered to the respective predetermined portions.
  • the fifth embodiment of the device according to this invention is constructed as shown in fig. 19.
  • This embodiment has substantially the same structure as that of the above-described fourth embodiment shown in fig. 18, but differs from the fourth embodiment in that lead portions 51 a1 , 51 b1 , 52 a1 , 51 b1 contiguous to the electric wires 51a, 51b are arranged such that the spacing between two sets of lead portions is gradually widened as the lead wires approach the fluorescent display screen surface 53a.
  • this invention is not limited to the described first to fifth embodiments, but includes various implementations which can be considered to be identical in principle in the method of suppressing magnetic flux.
  • electric wires 51, 51b may be connected in series with both ends of the horizontal deflection coils 50a, 50b as shown in fig. 7D, or they may be connected, as shown in figs. 7B and 7C, in parallel with electric wires 51a, 51b to which inductance L or resistance R is connected in parallel to adjust a current flowing therein, thus to balance such a leakage magnetic flux.
  • values of leakage magnetic flux from the fluorescent display screen surface 53a in the case of the embodiments according to this invention shown in fig. 6 and figs. 7a to 7d and in the case where this invention is not implemented (no measure is taken), which are measured at positions installed of the above-described antennas A0 to A15, B0 to B15, C0 to C15, D0 to D15, and E0 to E15 shown in figs. 3 and 4 are shown in the following Table.
  • the method according to this invention advantageously permits the change rate and the strength of leakage magnetic flux to be reduced to about 1/3 to 1/7 of those of the method in which no measure is taken.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Video Image Reproduction Devices For Color Tv Systems (AREA)
EP89311241A 1988-10-31 1989-10-31 Method and device for suppression of leakage of magnetic flux in display apparatus Expired - Lifetime EP0371618B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP63274672A JP2707293B2 (ja) 1988-10-31 1988-10-31 陰極線管表示装置の漏洩磁束低減方法及びその装置
JP274672/88 1988-10-31

Publications (2)

Publication Number Publication Date
EP0371618A1 EP0371618A1 (en) 1990-06-06
EP0371618B1 true EP0371618B1 (en) 1997-01-15

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EP89311241A Expired - Lifetime EP0371618B1 (en) 1988-10-31 1989-10-31 Method and device for suppression of leakage of magnetic flux in display apparatus

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EP (1) EP0371618B1 (ja)
JP (1) JP2707293B2 (ja)
KR (1) KR910009248B1 (ja)
DE (1) DE68927668T2 (ja)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0485559U (ja) * 1990-11-29 1992-07-24
JPH02134090A (ja) * 1988-11-15 1990-05-23 Victor Co Of Japan Ltd 陰極線管表示装置の漏洩磁束低減方法及びその装置
US5350973A (en) * 1989-08-31 1994-09-27 Kabushiki Kaisha Toshiba Cathode-ray tube apparatus having a reduced leak of magnetic fluxes
KR930000354B1 (ko) * 1989-08-31 1993-01-16 가부시끼가이샤 도시바 누설자속을 경감할 수 있는 음극선관장치
JP2003068228A (ja) * 2001-08-27 2003-03-07 Toshiba Corp 偏向ヨーク装置

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NL8602397A (nl) * 1985-10-25 1987-05-18 Philips Nv Beeldweergeefinrichting met ontstoringsmiddelen.

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Publication number Publication date
JP2707293B2 (ja) 1998-01-28
EP0371618A1 (en) 1990-06-06
KR900007040A (ko) 1990-05-09
KR910009248B1 (ko) 1991-11-07
DE68927668T2 (de) 1997-05-07
DE68927668D1 (de) 1997-02-27
JPH02121487A (ja) 1990-05-09

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