EP0708474A1 - Unité d'affichage à tube à rayons cathodiques dans laquelle les champs électriques radiant non-désirés venant de l'écran sont réduits - Google Patents

Unité d'affichage à tube à rayons cathodiques dans laquelle les champs électriques radiant non-désirés venant de l'écran sont réduits Download PDF

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Publication number
EP0708474A1
EP0708474A1 EP95116440A EP95116440A EP0708474A1 EP 0708474 A1 EP0708474 A1 EP 0708474A1 EP 95116440 A EP95116440 A EP 95116440A EP 95116440 A EP95116440 A EP 95116440A EP 0708474 A1 EP0708474 A1 EP 0708474A1
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EP
European Patent Office
Prior art keywords
cathode
ray tube
pulse voltage
conductive coating
reverse pulse
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Application number
EP95116440A
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German (de)
English (en)
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EP0708474B1 (fr
Inventor
Hiroshi Jitsukata
Katsuyuki Kawakami
Soichi Sakurai
Hiroshi Yoshioka
Yoshio Satoh
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Hitachi Ltd
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Hitachi Ltd
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Priority claimed from JP25320894A external-priority patent/JP3218887B2/ja
Priority claimed from JP6303808A external-priority patent/JPH08163474A/ja
Application filed by Hitachi Ltd filed Critical Hitachi Ltd
Publication of EP0708474A1 publication Critical patent/EP0708474A1/fr
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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
    • H01J29/003—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 an image display unit using a cathode-ray tube, and more particularly to a cathode-ray tube display unit having a mechanism for controlling an alternating electric field radiated frontward from a screen of a cathode-ray tube.
  • a cathode-ray tube display unit is composed of a high-frequency signal processing circuit, a deflection magnetic field generating circuit for an electron beam, a high-voltage generating circuit or the like.
  • the alternating electric field is classified into two types depending on a frequency band, and an alternating electric field having a frequency of 2 kHz to 400 kHz is referred to as a Very Low frequency Electric Field (VLEF), and an alternating electric field having a frequency of 5 Hz to 2 kHz is referred to as an Extremely Low frequency Electric Field (ELEF).
  • VLEF Very Low frequency Electric Field
  • EUF Extremely Low frequency Electric Field
  • an electric field value 1.0 [V/m] or below (30 cm in front of and 50 cm around the display unit) with respect to the VLEF in a band of 2 kHz to 400 kHz, and an electric field value 10 [V/m] or below (only 30 cm in front of the display unit) with respect to the ELEF in a band of 5 Hz to 2 kHz are specified, respectively.
  • a conductive layer is formed at a neck portion from a funnel portion of a cathode-ray tube and conductive coating is grounded electrically, thereby to shield an alternating electric field emitted from a deflection yoke so as to control an alternating electric field VLEF radiated from a cathode-ray tube display unit in some units.
  • the alternating electric field ELEF is an alternating electric field generated by a cause that a beam current is changed by the contents of an image regenerated by DC high voltage supplied from a high voltage circuit to a cathode-ray tube, thus producing dynamic voltage fluctuation, and a countermeasure with the prior art has been insufficient.
  • the present invention provides an electrode (hereinafter described as a funnel electrode) at a portion where there is no exterior graphite coating being in contact with an external wall of a glass vessel of a cathode-ray tube.
  • Reverse pulse voltage (amplitude V1) having a polarity inverted from that of pulse voltage (amplitude V0) supplied to a horizontal deflection coil is applied to the funnel electrode described above.
  • electrostatic capacities between the interior conductive coating of the cathode-ray tube and the horizontal deflection coil, and between the interior conductive coating and the above-mentioned funnel electrode are C0 and C1, respectively, and it is arranged so that a voltage value of (V0 ⁇ C0) becomes larger than a voltage value of (V1 ⁇ C1).
  • a transparent conductive coating having a resistance value per unit area at 2 ⁇ 106 [ ⁇ / sq.] or below is provided on an external surface of a face plate and is connected to ground.
  • a flyback pulse generated in a horizontal deflection coil is applied to a primary winding of a transformer connected to the coil, thereby to generate a reverse pulse having a polarity inverted from that of the flyback pulse is generated in a secondary winding of the transformer.
  • the unit is structured so that the reverse pulse is supplied to one end of a capacitor contained in a high voltage transformer and connected to a high voltage terminal at the other end, and the reverse pulse is applied to an interior conductive coating of a cathode-ray tube through an anode cable.
  • a secondary winding of a transformer for generating a first reverse pulse having a polarity inverted from that of a flyback pulse produced in a horizontal deflection coil and an auxiliary winding of a high voltage transformer for generating a pulse generated during a flyback period, i.e., a second reverse pulse having a polarity inverted from that of a residual pulse remaining in a high voltage line at a high voltage terminal of the high voltage transformer are connected with each other, thus generating voltage obtained by adding and synthesizing first and second reverse pulses.
  • the unit is structured so that the added and synthesized reverse pulse is supplied to one end of a capacitor connected to a high voltage terminal or an anode cable at the other end, and the synthesized reverse pulse is applied to an interior conductive coating of a cathode-ray tube.
  • alternating voltage which is originated in pulse voltage supplied to a deflection yoke and has been generated in an interior conductive coating of a cathode-ray tube by electrostatic coupling is canceled by pulse voltage generated in the interior conductive coating with reverse pulse voltage applied to the funnel electrode, thereby to reduce the amplitude of alternating voltage which has been generated in the interior conductive coating.
  • VLEF alternating electric field
  • Fig. 1 is an explanatory view showing a principal part of a first embodiment of a cathode-ray tube display unit according to the present invention from the side thereof
  • Fig. 2 is an explanatory view showing a cathode-ray tube from the rear
  • Fig. 3 shows a sectional view of alternating electric field radiated from a cathode-ray tube device.
  • a cathode-ray tube 1 consists roughly of three glass vessels, and is composed of a face plate portion 3, a funnel portion 2 and a neck portion 7. At least the face plate 3 is provided with a fluorescent plane obtained by applying a phosphor (not shown) to the inside of transparent glass.
  • the funnel portion 2 is an almost cone-shaped glass vessel, and is provided at least with an anode button 9 for applying high voltage (hereinafter abbreviated as H.V.) from a high voltage deflection circuit 20, an exterior graphite coating 5 and a funnel electrode 8.
  • the exterior graphite coating 5 is obtained by applying an aqueous solution of graphite which is an electrical conductor to a part of the external wall of the glass vessel of the funnel 2 and drying it.
  • the exterior graphite coating 5 is connected electrically to ground so as to add electrostatic capacity to an anode of the cathode-ray tube 1.
  • An electron gun (not shown) for generating an electron beam is sealed in the neck portion 7, and at least a deflection yoke 6 is installed from the outside thereof.
  • the deflection yoke 6 installed on the neck portion 7 consists of a horizontal deflection coil and a vertical deflection coil for generating deflection magnetic field for deflecting an electron beam horizontally and vertically so as to obtain a raster.
  • a metal band (an explosion-proof band) 4 for increasing safety when the glass vessel of a cathode-ray tube is damaged is wound around the side portion of the face plate 3, and is used by connecting it electrically to ground.
  • an inner layer conductive coating 13 in which conductive graphite is applied is formed on the inside of the funnel 2, and D.C. voltage at several ten thousand [V] is supplied thereto from a terminal T4 of a high voltage deflection circuit 20 through the anode button 9.
  • a phosphor that emits light by irradiation with an electron beam is applied to the inside of the face plate 3 so as to form a fluorescent film 11, and electric connection is made with a metal-back film 12 obtained by vaporizing aluminum so that the fluorescent film 11 and the interior conductive coating 13 show the same potential.
  • a color selecting electrode such as a shadow mask for selecting color phosphors in three primary colors is provided near by the fluorescent film 11 so that it shows the same potential as that of the interior conductive coating 13 in the case of a color cathode-ray tube.
  • the exterior graphite coating 5 is connected to ground, and electrostatic capacity C5 of approximately several thousands [pF] is formed between the exterior graphite coating 5 and the interior conductive coating 13 through the funnel glass and used as the smoothing capacity of the high voltage circuit 20.
  • a funnel electrode 8 that constitutes a principal part of the present invention between the grounded exterior graphite coating 5 and the deflection yoke 6.
  • a conductive coating film is formed on the external surface of the glass face of the funnel 2
  • a metal foil such as a copper foil having a thickness of approximately 35 ⁇ m
  • water soluble graphite is applied and dried
  • the funnel electrode 8 in which an electrode is provided in contact with the external wall of the glass vessel at the funnel portion.
  • the horizontal deflection coil of the deflection yoke 6 is connected to terminals T1 and T2 of the high voltage deflection circuit 20 shown in Fig. 1, and pulse voltage V0 of approximately 1,000 [V p-p ] that repeats at a horizontal deflection period (hereinafter abbreviated as H period.
  • the period is a reciprocal number of a horizontal deflection frequency f H .) such as shown in Fig. 3B is supplied from T2.
  • a sawtooth current of a horizontal period is generated in the horizontal deflection coil by pulse voltage V0, thereby to generate a horizontal deflection magnetic field that deflects an electron beam from side to side.
  • reverse pulse voltage V1 that has a similar figure to the pulse voltage V0 at the terminal T2 and a polarity inverted from that of V0 is generated at the terminal T3 of the high voltage deflection circuit 20, and the voltage V1 is supplied to the funnel electrode 8.
  • the VLEF 100 in a frequency band of 2 kHz to 400 kHz is an alternating electric field of H period originated in the pulse voltage V0 supplied to the deflection yoke 6.
  • the ELEF 200 in a frequency band of 5 Hz to 2 kHz is an alternating electric field caused by a fact that an electron beam quantity emitted from the electron gun of the cathode-ray tube 1 is changed in accordance with the contents of a video signal and dynamic voltage fluctuation (abbreviated as ⁇ HV) in a vertical deflection period (hereinafter abbreviated as V period.
  • the period is a reciprocal number of a vertical deflection frequency f V .) is generated by H.V. supplied to the anode of the cathode-ray tube 1. (See Fig. 3C.)
  • Pulse voltage V01 (Fig. 3B) analogous to the pulse voltage V0 supplied from the terminal T2 is generated in the interior conductive coating 13 by electrostatic coupling between the horizontal deflection coil of the deflection yoke 6 and the interior conductive coating 13 (distributed capacity is expressed as equivalent electrostatic capacity C0 in Fig. 3A).
  • pulse voltage V11 (Fig. 3B) analogous to the reverse pulse voltage V1 supplied to the funnel electrode 8 from the terminal T3 is generated between the funnel electrode 8 and the interior conductive coating 13 by electrostatic coupling between the funnel electrode 8 and the interior conductive coating 13 (equivalent electrostatic capacity is expressed as C1 in Fig. 3A).
  • Fig. 4 shows an equivalent circuit for explaining connected states of electrostatic capacities C0, C1 or the like, and a point P corresponds to the interior conductive coating 13.
  • C5 represents electrostatic capacity between the exterior graphite coating 5 and the interior conductive coating 13
  • R5 represents resistance of the exterior graphite coating 5
  • C10 represents electrostatic capacity between a transparent conductive coating 10 (expressed with a point Q) formed on the surface of the face plate 3 and the interior conductive coating 13
  • R10 represents the resistance of the transparent conductive coating 10.
  • C20 and R20 represent internal capacity and protective resistance of a flyback transformer (FBT) of the high voltage deflection circuit 20.
  • FBT flyback transformer
  • the alternating voltage When dynamic voltage change (alternating voltage) is generated in the interior conductive coating 13, the alternating voltage is generated in the transparent conductive coating 10 formed on the surface of the face plate 3 through the capacity C10.
  • the alternating voltage generated at the point Q generates voltage amplitude in accordance with a ratio of impedance division of the electrostatic capacity C10 and the resistance R10 in the transparent conductive coating 10, and radiates the alternating electric fields VLEF 100 and ELEF 200 frontward from the face plate 3. Accordingly, when the resistance value R10 of the transparent conductive coating 10 can be made sufficiently small, thereby to make the shielding effect larger, the alternating voltage generated at the point Q becomes smaller, thus making it possible to control the alternating electric field to a small value.
  • the cause of generating the alternating electric field VLEF 100 is attributed to a fact that alternating voltage V01 analogous to the pulse voltage V0 supplied to the terminal T2 is generated in the interior conductive coating 13 due to the existence of the electrostatic capacity C0.
  • the alternating voltage V01 at the point P in Fig. 4 is expressed with the following expression, and is approximated with Expression 1 since Z00 ⁇ Z0.
  • the amplitude of the generated voltage V01 is proportioned to a product (C0 ⁇ V0) of electrostatic capacity C0 of the horizontal deflection coil and the pulse voltage V0 supplied to the horizontal deflection coil.
  • alternating voltage V11 analogous to the reverse pulse voltage V1 applied to the electrode is generated in the interior conductive coating 13 by the electrostatic capacity C1 of the funnel electrode 8.
  • the synthetic impedance between the point P and the ground is Z11
  • the impedance of C1 is Z1 at the point P in Fig. 4
  • the alternating voltage V11 at the point P is approximated with Expression 2 since Z11 ⁇ Z1.
  • FIG. 7 shows the results of measuring VLEF by installing a measuring instrument of an alternating electric field (such as EFM 200 manufactured by Combinova Company in Sweden) at a distance of 30 cm from the tube face in front of the cathode-ray tube device 1.
  • a measuring instrument of an alternating electric field such as EFM 200 manufactured by Combinova Company in Sweden
  • the present invention it is possible to bring the alternating electric field value of VLEF to a TCO guide line ( ⁇ 1 [V/m]) or lower by setting the electrostatic capacity C11 of the funnel electrode 8 and the reverse pulse voltage V1 appropriately, and to improve it to a level that the influence of unwanted radiation electric field on the human body offers no problem.
  • Table 1 shows values of the constant K computed from the results of experiments with respect to three types of deflection yokes #1, #2 and #3 having different specifications, and K was within the range of 0.1 to 0.9. Besides, the constant K of the deflection yoke #2 of the data shown in Fig. 6 and Fig. 7 was approximately 0.5.
  • the electrostatic capacity C1 of the funnel electrode 8 can be set depending on the size of the electrode area, and is not related so much to the electrode configuration and the position of installing the electrode. Accordingly, the configuration and installing position of the electrode are not limited to those that are shown in Fig. 1, but, as shown in Fig. 8 for instance, it is possible to arrange a funnel electrode 88 having an optional configuration in the area where no exterior graphite coating 5 exists.
  • the alternating voltage V01 of the interior conductive coating 13 that becomes a generating source of the alternating electric field VLEF 100 is proportioned to the electrostatic capacity C0 as shown in the Expression 1.
  • the funnel electrode capacity C1 required for controlling VLEF or the reverse pulse voltage V1 can be made small if C0 can be reduced, it becomes an advantage in executing the present invention.
  • electrostatic capacity C of a plane parallel plate capacitor is expressed by Expression 5.
  • the interior conductive coating 13 opposing to the horizontal deflection coil is formed in a mesh shape or the like, and the equivalent area S is reduced by chipping a part thereof.
  • d is increased by increasing the glass vessel thickness (corresponding to d) at the portion opposing to the horizontal deflection coil toward the inside of the vessel. It has been confirmed that it is possible to make the electrostatic capacity C0 to 90 [pF] or less and to control the alternating electric field VLEF with practical values of the area of the funnel electrode and the reverse pulse voltage value that have no problem in point of withstand voltage by using the foregoings independently or jointly.
  • FIG. 9A is a side view of the deflection yoke 6
  • Fig. 9B is an explanatory diagram for explaining magnetic flux of a core made of a magnetic material.
  • the deflection yoke 6 is provided with a vertical deflection coil 61 (not shown in Fig. 9B) and a horizontal deflection coil 62 on the inside of the core 60 made of a magnetic material.
  • an auxiliary winding 64 for detecting magnetic flux 63 generated by the horizontal deflection coil 62 is provided in the core portion 60.
  • the horizontal deflection magnetic field 63 interlinks with the auxiliary winding 64, and the reverse pulse voltage V1 is obtainable at a terminal T3.
  • the pulse voltage detected from the terminal T2 where pulse voltage V0 is applied to the deflection yoke 6 is attenuated so as to show a predetermined amplitude, and pulse voltage inverted by a transistor is supplied thereafter to the funnel electrode 8 as reverse pulse voltage V1 and used to control the alternating electric field VLEF.
  • an alternating electric field ELEF 200 in a frequency band of 5 Hz to 2 kHz is caused to be generated with ⁇ HV that is high voltage dynamic voltage fluctuation shown in Fig. 3C, being different from the alternating electric field VLEF described previously.
  • a transparent conductive coating 10 with a resistance value set at the optimum is provided on the surface of the face plate 3 of the cathode-ray tube 1 in order to control the alternating electric field ELEF 200.
  • Those in which particles of indium oxide or tin oxide are dispersed are used as the material of the transparent conductive film.
  • a thin coating (not illustrated in Fig.
  • Fig. 11 shows the result of measuring the relationship between the resistance value (unit [ ⁇ /sq.]) per unit area of the transparent conductive coating 10 and the alternating electric field ELEF at a distance of 30 [cm] in the front of the cathode-ray tube display unit 1.
  • a regulated value ⁇ 10 [V/m]
  • ELEF the distance at 30 cm in the front
  • Fig. 12 shows frequency characteristics of a resistance value of a general transparent conductive coating.
  • a transparent conductive coating of high production cost has small resistance values in the frequency areas of two types of alternating electric fields ELEF and VLEF, and can shield two types of alternating electric fields sufficiently.
  • the cost of this transparent conductive coating is high and has been used only for a part of high-grade types.
  • a transparent conductive coating of low production cost has a small resistance value in the frequency area of the ELEF band, it has a drawback that the resistance value is increased when the frequency is increased and the shielding effect of the alternating electric field VLEF is decreased.
  • Fig. 13 shows another embodiment in which alternating voltage generated in an interior conductive coating is canceled.
  • the reverse pulse voltage is applied by superimposing on high voltage.
  • the deflection yoke 6 is provided with a horizontal deflection coil 62 and a vertical deflection coil 61 for generating deflection magnetic fields for obtaining a raster by deflecting an electron beam in a horizontal and a vertical directions. (Besides, the details of the horizontal and vertical deflection coils are omitted in view of illustration circumstances).
  • the horizontal deflection coil 62 is connected to the horizontal deflection circuit 50, and pulse voltage V0 that repeats at the horizontal period is applied thereto.
  • a high voltage transformer 20 boosts a pulse applied to a primary coil 21 from a high voltage circuit 51 with a secondary coil 22.
  • the boosted pulse is rectified with a diode 23 and smoothed by a capacitor C2, and outputs DC voltage at several ten thousands V at a high voltage terminal T4.
  • an inner layer conductive coating 13 obtained by applying conductive graphite is formed on an internal surface of a glass vessel of a funnel portion 2, and high voltage (HV) from the high voltage terminal T4 is applied thereto through an anode button 9.
  • a phosphor that emits light by irradiation with an electron beam is applied to the internal face of a face plate 3 so as to form a fluorescent film 11 thereon, and a metal-back film 12 deposited with aluminum and an interior conductive coating 13 are connected electrically to each other so that high voltage is applied to the fluorescent film 11.
  • the exterior graphite coating 5 is composed of that in which an aqueous solution of graphite that is an electrical conductor is applied to a part of the external wall of the glass vessel of the funnel portion 2 and dried, and this exterior graphite coating 5 is connected electrically with ground thereby to add electrostatic capacity to the anode of the cathode-ray tube 1.
  • the exterior graphite coating 5 connected to ground forms electrostatic capacity (exterior capacity) C5 between the exterior graphite coating 5 and the interior conductive coating 13 through the funnel glass. Since this electrostatic capacity C5 is connected in parallel with a smoothing capacitor C2 of the high voltage transformer 20, it has a function of reducing fluctuation (ripple) of high voltage (HV) outputted from the high voltage terminal T4.
  • the horizontal deflection coil 62 of the deflection yoke 6 and the interior conductive coating 13 are opposed to each other through glass having a thickness of approximately 2 mm.
  • electrostatic capacity C0 in Fig. 14 a pulse V01 analogous to a flyback pulse V0 applied to the horizontal deflection coil 62 is generated in the interior conductive coating 13 as shown in Fig. 3B.
  • the amplitude of this pulse V01 is determined being proportioned to a product of electrostatic capacity C0 between the horizontal deflection coil 62 and the interior conductive coating 13 and the amplitude of the flyback pulse V0, and inversely proportioned to the sum of the high voltage smoothing capacitor C2 and the exterior capacitor C5. It is expressed by Expression 6 as follows.
  • an alternating electric field VLEF 100 is radiated frontward from the face plate portion 3 by a fact that alternating voltage (pulse V01) fluctuating at a horizontal deflection frequency f H is generated with the metal-back film 12 of the conductive coating and the interior conductive coating 13 as electrodes.
  • the reverse pulse V1 is a pulse generated in a secondary winding 32 of a transformer 30 connected to the horizontal deflection circuit 50 and the horizontal deflection coil 61, and polarities of V0 and V1 are inverted from each other.
  • the reverse pulse V1 supplied to a terminal 26 of the high voltage transformer 20 is applied to a high voltage terminal T4 through a capacitor 25 contained inside the high voltage transformer 20 and generates a reverse pulse V11 in the interior conductive coating 13.
  • One end of the capacitor 25 is connected to the high voltage terminal T4, and the capacitor 25 is contained inside the high voltage transformer 20 from a viewpoint of withstand voltage and safety and used being filled with resin having high insulating property.
  • the amplitude of the reverse pulse V11 is determined depending on the number of windings of the secondary winding 32 of the transformer 30 and an electrostatic capacity value of the capacitor 25 contained inside the high voltage transformer 20.
  • the pulse V01 and the reverse pulse V11 generated in the interior conductive coating 13 are set so that absolute values thereof become almost equal to each other, the pulse V01 and the reverse pulse V11 negate each other, thus making it possible to make the amplitude of the alternating voltage generated in the interior conductive coating 13 almost zero.
  • a pulse V01 of approximately 10 V p-p has been generated in the interior conductive coating 13 by means of a flyback pulse V0 of 1000 V p-p .
  • a reverse pulse V1 of -220 V p-p was supplied through a capacitor 25 having electrostatic capacity of 150 pF.
  • an alternating electric field measuring instrument such as EFM 200 manufactured by Combinova Company in Sweden
  • EFM 200 manufactured by Combinova Company in Sweden
  • VLEF has been improved to a level that it can be made to a TCO guide line ( ⁇ 1 V/m) or below and influence by unwanted radiation electric field on human bodies offers no problem.
  • the capacity of the capacitor 25 to which the reverse pulse voltage V1 is applied is C25, (V 0 ⁇ C 0 ) > (V 1 ⁇ C 25 ) is obtained.
  • Fig. 15 shows another embodiment of the present invention.
  • One end of a primary winding of the transformer 30 is connected to the power source in Fig. 13, but it is connected to reference potential (GND) through a capacitor in Fig. 15.
  • GND reference potential
  • the horizontal deflection circuit 50 is connected to the power source through an inductance 44, and energy is supplied thereto. Further, a primary coil 41 of a transformer 40 is connected to a horizontal deflection coil 62, and a reverse pulse V1 with a polarity inverted from that of a flyback pulse V0 generated in the primary coil 41 is generated in a secondary coil 42 of the transformer 40.
  • This reverse pulse V1 is supplied to a terminal 26 of a high voltage transformer 20 and negates the pulse V01 in the interior conductive coating 13, thereby to reduce the alternating electric field VLEF 100.
  • Fig. 16 shows another embodiment of the present invention.
  • a high voltage circuit 51 is operated with a video synchronizing signal as reference, and the pulse boosted in the secondary winding 22 of the high voltage transformer 20 cannot be smoothed completely, but the ripple (voltage fluctuation) thereof remains at an output terminal 27.
  • the influence by the fluctuating portion is canceled.
  • a second reverse pulse V3 obtained from an auxiliary winding 28 provided in the high voltage transformer 20 is superimposed on the first reverse pulse V1 obtained from the secondary coil 32 of the transformer 30 described with reference to Fig. 13 or from the secondary coil 42 of the transformer 40 described with reference to Fig. 15.
  • a reverse pulse (V1 + V3) obtained by adding and synthesizing these two reverse pulses V1 and V3 is supplied to a terminal 26 connected to one end of a capacitor 25 so as to obtain a reverse pulse (V11 + V31) that cancels the alternating voltage generated in the interior conductive coating 13.
  • Fig. 17A shows a flyback pulse V0 and a pulse V01 generated in the interior conductive coating 13
  • Fig. 17B shows AC components generated in the high voltage transformer 20 and shows a residual pulse V2 remaining on a high voltage line generated during a flyback period and a pulse V21 generated in the interior conductive coating 13 being caused by V2.
  • the flyback pulse V0 and the residual pulse V2 generated in the horizontal deflection circuit 50 and the high voltage circuit 51 have phases different by ⁇ t (approximately several ⁇ seconds). As a result, as shown in Fig.
  • the alternating voltage generated in the interior conductive coating 13 becomes voltage (V01 + V21) obtained by adding pulses V01 and V21 to each other.
  • the first reverse pulse V1 and the second pulse V3 shown in Figs. 17D and 17E are added to each other so as to obtain a reverse pulse (V11 + V31) shown in Fig. 17F in the interior conductive coating 13, thus making it possible to negate the pulse (V01 + V21) with each other and to reduce the alternating electric field VLEF 100 to almost zero.
  • Fig. 18 shows a structure for supplying a reverse pulse to the interior conductive coating 13 in a cathode-ray tube display unit according to another embodiment of the present invention.
  • a first anode cable 91 for applying high voltage (HV) from the high voltage transformer 20 to the cathode-ray tube 1 is connected to one end of a second anode cable 92 inside an anode cap 90 composed of an elastic insulator, and another end of the anode cable 92 is connected to one end of a capacitor 94.
  • HV high voltage
  • the capacitor 94 is housed in a vessel 93 made of resin, resin of high withstand voltage property is filled in the vessel 93, and another end of the capacitor 94 is connected to an electric cable 95.
  • the function of the capacitor 94 is similar to that of the capacitor 25 in respective embodiments described above. Hence, the description thereof is omitted.
  • Fig. 19 shows another structure for supplying a reverse pulse to the interior conductive coating 13
  • Fig. 19 is a perspective view showing an anode cable and an anode cap
  • Fig. 20 is a sectional view taken along a line XX-XX of the anode cable shown in Fig. 19.
  • the present embodiment has such a structure that a conductor 96 having a predetermined length is arranged almost coaxially with a core line 97 to which high voltage (HV) is applied on a circumferential portion of the anode cable 91 from the high voltage transformer 20.
  • HV high voltage
  • electrostatic capacity (not illustrated) between the circumferential conductor 96 and the core line 97, and, when the pulse V1 or the reverse pulse (V1 + V3) obtained in respective embodiments is applied to the circumferential conductor 96, a reverse pulse V11 or a reverse pulse (V11 + V31) can be obtained in the interior conductive coating 13 of the cathode-ray tube 1 by the electrostatic capacity.
  • a reverse pulse V11 or a reverse pulse V11 + V31
  • the reverse pulse V1 may be inputted to the terminal 26 shown in Fig. 13 using that which has been obtained from the auxiliary winding 64 shown in Fig. 9A or that which has been obtained from the circuit shown in Fig. 10 or may be applied using structures shown in Figs. 18 and 19.
EP19950116440 1994-10-19 1995-10-18 Unité d'affichage à tube à rayons cathodiques dans laquelle les champs électriques radiant non-désirés venant de l'écran sont réduits Expired - Lifetime EP0708474B1 (fr)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
JP25320894A JP3218887B2 (ja) 1994-10-19 1994-10-19 陰極線管表示装置
JP25320894 1994-10-19
JP253208/94 1994-10-19
JP30380894 1994-12-07
JP6303808A JPH08163474A (ja) 1994-12-07 1994-12-07 陰極線管表示装置
JP303808/94 1994-12-07

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EP0708474A1 true EP0708474A1 (fr) 1996-04-24
EP0708474B1 EP0708474B1 (fr) 2000-09-06

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EP (1) EP0708474B1 (fr)
KR (1) KR100204724B1 (fr)
DE (1) DE69518713T2 (fr)
TW (1) TW395550U (fr)

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GB2306872A (en) * 1995-10-27 1997-05-07 Samsung Electronics Co Ltd An electromagnetic field shielding circuit for a display
GB2309367A (en) * 1996-01-18 1997-07-23 Hitachi Media Electron Kk Reducing stray electric fields in displays
EP0821389A2 (fr) * 1996-07-25 1998-01-28 Kabushiki Kaisha Toshiba Tube à rayons cathodiques et appareil de tube à rayons cathodiques
NL1004613C2 (nl) * 1995-11-29 1998-07-27 Mitsubishi Electric Corp Elektronenstraalbuisinrchting.
US7514686B2 (en) 2004-08-10 2009-04-07 Canon Kabushiki Kaisha Radiation detecting apparatus, scintillator panel, their manufacturing method and radiation detecting system

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DE102011086646B4 (de) 2011-11-18 2013-06-27 Siemens Aktiengesellschaft Bildschirm und Verfahren zur Ansteuerung eines Bildschirms
TWM479825U (zh) 2013-10-01 2014-06-11 Jin-Tan Huang 可標示旋轉行程的手工具

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EP0498589A2 (fr) * 1991-02-07 1992-08-12 Nokia Display Products Oy Procédé et circuit pour diminuer les radiations nocives émises par un tube à rayons cathodiques
WO1993010537A1 (fr) * 1991-11-22 1993-05-27 Icl Systems Aktiebolag Dispositif et procede pour diminuer le champ electrique alternatif produit dans leur voisinage/par des unites de visualisation
US5231332A (en) * 1992-04-15 1993-07-27 Zenith Electronics Corporation AC electric field emission suppression in CRT image displays
JPH05283020A (ja) 1992-03-31 1993-10-29 Sony Corp 陰極線管

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EP0498589A2 (fr) * 1991-02-07 1992-08-12 Nokia Display Products Oy Procédé et circuit pour diminuer les radiations nocives émises par un tube à rayons cathodiques
WO1993010537A1 (fr) * 1991-11-22 1993-05-27 Icl Systems Aktiebolag Dispositif et procede pour diminuer le champ electrique alternatif produit dans leur voisinage/par des unites de visualisation
JPH05283020A (ja) 1992-03-31 1993-10-29 Sony Corp 陰極線管
US5231332A (en) * 1992-04-15 1993-07-27 Zenith Electronics Corporation AC electric field emission suppression in CRT image displays

Cited By (8)

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Publication number Priority date Publication date Assignee Title
GB2306872A (en) * 1995-10-27 1997-05-07 Samsung Electronics Co Ltd An electromagnetic field shielding circuit for a display
GB2306872B (en) * 1995-10-27 2000-03-29 Samsung Electronics Co Ltd An electromagnetic field shielding circuit for a display
NL1004613C2 (nl) * 1995-11-29 1998-07-27 Mitsubishi Electric Corp Elektronenstraalbuisinrchting.
GB2309367A (en) * 1996-01-18 1997-07-23 Hitachi Media Electron Kk Reducing stray electric fields in displays
GB2309367B (en) * 1996-01-18 1999-12-29 Hitachi Media Electron Kk Display monitor
EP0821389A2 (fr) * 1996-07-25 1998-01-28 Kabushiki Kaisha Toshiba Tube à rayons cathodiques et appareil de tube à rayons cathodiques
EP0821389A3 (fr) * 1996-07-25 1998-12-02 Kabushiki Kaisha Toshiba Tube à rayons cathodiques et appareil de tube à rayons cathodiques
US7514686B2 (en) 2004-08-10 2009-04-07 Canon Kabushiki Kaisha Radiation detecting apparatus, scintillator panel, their manufacturing method and radiation detecting system

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KR100204724B1 (ko) 1999-06-15
DE69518713D1 (de) 2000-10-12
EP0708474B1 (fr) 2000-09-06
DE69518713T2 (de) 2001-05-31
TW395550U (en) 2000-06-21

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