EP0708474B1 - 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
EP0708474B1
EP0708474B1 EP19950116440 EP95116440A EP0708474B1 EP 0708474 B1 EP0708474 B1 EP 0708474B1 EP 19950116440 EP19950116440 EP 19950116440 EP 95116440 A EP95116440 A EP 95116440A EP 0708474 B1 EP0708474 B1 EP 0708474B1
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EP
European Patent Office
Prior art keywords
cathode
ray tube
display unit
reverse pulse
voltage
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.)
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EP19950116440
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German (de)
English (en)
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EP0708474A1 (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
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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.
  • US-A-5,231,332 described an AC electric field emission suppressor for use in a CRT imaging system.
  • the flyback pulse voltage and the reverse pulse voltage are set having an opposite polarity and substantially the same amplitude.
  • a conductive film electrode may be provided at a funnel portion of the cathode-ray tube where no exterior graphite coating is present. Then, said electrostatic capacity C 1 is the electrostatic capacity between said conductive film electrode and said interior conductive coating.
  • a transparent conductive coating having a resistance value per unit area at 2 ⁇ 10 6 [ ⁇ /sq.] or below may be 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 T 4 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 C 5 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 T 1 and T 2 of the high voltage deflection circuit 20 shown in Fig. 1, and pulse voltage V 0 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 T 2 .
  • a sawtooth current of a horizontal period is generated in the horizontal deflection coil by pulse voltage V 0 , thereby to generate a horizontal deflection magnetic field that deflects an electron beam from side to side.
  • reverse pulse voltage V 1 that has a similar figure to the pulse voltage V 0 at the terminal T 2 and a polarity inverted from that of V 0 is generated at the terminal T 3 of the high voltage deflection circuit 20, and the voltage V 1 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 V 0 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 V 01 (Fig. 3B) analogous to the pulse voltage V 0 supplied from the terminal T 2 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 C 0 in Fig. 3A).
  • pulse voltage V 11 (Fig. 3B) analogous to the reverse pulse voltage V 1 supplied to the funnel electrode 8 from the terminal T 3 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 C 1 in Fig. 3A).
  • Fig. 4 shows an equivalent circuit for explaining connected states of electrostatic capacities C 0 , C 1 or the like, and a point P corresponds to the interior conductive coating 13.
  • C 5 represents electrostatic capacity between the exterior graphite coating 5 and the interior conductive coating 13
  • R 5 represents resistance of the exterior graphite coating 5
  • C 10 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
  • R 10 represents the resistance of the transparent conductive coating 10.
  • C 20 and R 20 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 C 10 .
  • the alternating voltage generated at the point Q generates voltage amplitude in accordance with a ratio of impedance division of the electrostatic capacity C 10 and the resistance R 10 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 R 10 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 V 01 analogous to the pulse voltage V 0 supplied to the terminal T 2 is generated in the interior conductive coating 13 due to the existence of the electrostatic capacity C 0 .
  • the alternating voltage V 01 at the point P in Fig. 4 is expressed with the following expression, and is approximated with Expression 1 since Z 00 ⁇ Z 0 .
  • the amplitude of the generated voltage V 01 is proportioned to a product (C 0 ⁇ V 0 ) of electrostatic capacity C 0 of the horizontal deflection coil and the pulse voltage V 0 supplied to the horizontal deflection coil.
  • alternating voltage V 11 analogous to the reverse pulse voltage V 1 applied to the electrode is generated in the interior conductive coating 13 by the electrostatic capacity C 1 of the funnel electrode 8.
  • the synthetic impedance between the point P and the ground is Z 11
  • the impedance of C 1 is Z 1 at the point P in Fig. 4
  • the alternating voltage V 11 at the point P is approximated with Expression 2 since Z 11 ⁇ Z 1 .
  • 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 C 11 of the funnel electrode 8 and the reverse pulse voltage V 1 appropriately, and to improve it to a level that the influence of unwanted radiation electric field on the human body offers no problem.
  • a value of a constant K has been different depending on the specifications of the winding of the horizontal deflection coil of the deflection yoke 6 used in the experiments in a relational expression shown in Expression 4 with K as a constant.
  • K ⁇ (V 0 ⁇ C 0 ) (V 1 ⁇ C 1 )
  • 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.
  • 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 C 1 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.
  • 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 V 1 is obtainable at a terminal T 3 .
  • the pulse voltage detected from the terminal T 2 where pulse voltage V 0 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 V 1 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 V 0 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 C 2 , and outputs DC voltage at several ten thousands V at a high voltage terminal T 4 .
  • 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 T 4 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) C 5 between the exterior graphite coating 5 and the interior conductive coating 13 through the funnel glass. Since this electrostatic capacity C 5 is connected in parallel with a smoothing capacitor C 2 of the high voltage transformer 20, it has a function of reducing fluctuation (ripple) of high voltage (HV) outputted from the high voltage terminal T 4 .
  • 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 C 0 in Fig. 14 a pulse V 01 analogous to a flyback pulse V 0 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 V 01 is determined being proportioned to a product of electrostatic capacity C 0 between the horizontal deflection coil 62 and the interior conductive coating 13 and the amplitude of the flyback pulse V 0 , and inversely proportioned to the sum of the high voltage smoothing capacitor C 2 and the exterior capacitor C 5 .
  • the reverse pulse V 1 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 V 0 and V 1 are inverted from each other.
  • the reverse pulse V 1 supplied to a terminal 26 of the high voltage transformer 20 is applied to a high voltage terminal T 4 through a capacitor 25 contained inside the high voltage transformer 20 and generates a reverse pulse V 11 in the interior conductive coating 13.
  • One end of the capacitor 25 is connected to the high voltage terminal T 4 , 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 V 11 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 V 01 and the reverse pulse V 11 generated in the interior conductive coating 13 are set so that absolute values thereof become almost equal to each other, the pulse V 01 and the reverse pulse V 11 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 V 01 of approximately 10 V p-p has been generated in the interior conductive coating 13 by means of a flyback pulse V 0 of 1000 V p-p .
  • a reverse pulse V 1 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 V 1 is applied is C 25
  • (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 V 1 with a polarity inverted from that of a flyback pulse V 0 generated in the primary coil 41 is generated in a secondary coil 42 of the transformer 40.
  • This reverse pulse V 1 is supplied to a terminal 26 of a high voltage transformer 20 and negates the pulse V 01 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 V 3 obtained from an auxiliary winding 28 provided in the high voltage transformer 20 is superimposed on the first reverse pulse V 1 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 (V 1 + V 3 ) obtained by adding and synthesizing these two reverse pulses V 1 and V 3 is supplied to a terminal 26 connected to one end of a capacitor 25 so as to obtain a reverse pulse (V 11 + V 31 ) that cancels the alternating voltage generated in the interior conductive coating 13.
  • Fig. 17A shows a flyback pulse V 0 and a pulse V 01 generated in the interior conductive coating 13
  • Fig. 17B shows AC components generated in the high voltage transformer 20 and shows a residual pulse V 2 remaining on a high voltage line generated during a flyback period and a pulse V 21 generated in the interior conductive coating 13 being caused by V 2 .
  • the flyback pulse V 0 and the residual pulse V 2 generated in the horizontal deflection circuit 50 and the high voltage circuit 51 have phases different by ⁇ t (approximately several ⁇ seconds).
  • the alternating voltage generated in the interior conductive coating 13 becomes voltage (V 01 + V 21 ) obtained by adding pulses V 01 and V 21 to each other.
  • the first reverse pulse V 1 and the second pulse V 3 shown in Figs. 17D and 17E are added to each other so as to obtain a reverse pulse (V 11 + V 31 ) shown in Fig. 17F in the interior conductive coating 13, thus making it possible to negate the pulse (V 01 + V 21 ) 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 V 1 or the reverse pulse (V 1 + V 3 ) obtained in respective embodiments is applied to the circumferential conductor 96, a reverse pulse V 11 or a reverse pulse (V 11 + V 31 ) can be obtained in the interior conductive coating 13 of the cathode-ray tube 1 by the electrostatic capacity.
  • electrostatic capacity not illustrated
  • the reverse pulse V 1 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.

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Claims (18)

  1. Unité d'affichage à tube cathodique, comprenant:
    un moyen (20) à haute tension servant à fournir une haute tension à une anode d'un tube cathodique (1);
    un moyen formant collier de déviation (6) comportant une bobine de déviation horizontale et une bobine de déviation verticale;
    un moyen (20, T1, T2) servant à fournir une tension V0 par retour-ligne audit moyen formant collier de déviation (6);
    un revêtement conducteur intérieur (13) formé sur la face interne d'un récipient en verre dudit tube cathodique (1);
    un moyen (20, 64, 30, 40, 28, 32) pour générer une tension impulsionnelle inverse V1 à polarité inverse de celle d'une tension générée dans ledit revêtement conducteur intérieur (13), du fait d'un couplage électrostatique provoqué par ladite tension impulsionnelle V0 par retour-ligne; et
    un moyen pour appliquer ladite tension impulsionnelle inverse V1 audit revêtement conducteur intérieur (13) par l'intermédiaire d'une capacité électrostatique (8, 25); caractérisée en ce qu'une valeur de ladite tension impulsionnelle inverse V1 est établie de façon qu'une équation V01 - V11 ≈ 0 soit satisfaite, V01 étant une première tension alternative proportionnelle à un produit (V0 x C0), C0 étant une capacité électrostatique entre ladite bobine de déviation horizontale et ledit revêtement conducteur intérieur (13), et V11 étant une deuxième tension alternative proportionnelle à un produit (V1 x C1), où C1 est ladite capacité électrostatique (8, 25).
  2. Unité d'affichage à tube cathodique selon la revendication 1, comprenant:
    une électrode pelliculaire conductrice (8) formée sur une surface de paroi externe d'un récipient en verre d'une partie en entonnoir du tube cathodique (1), séparée électriquement d'un revêtement extérieur en graphite (5) formé sur une surface de paroi externe dudit tube cathodique (1), ledit revêtement en graphite (5) étant relié à la terre;
    ledit moyen (20, 64, 30, 40, 28, 32) pour générer une tension inverse V1 étant connecté à ladite électrode pelliculaire conductrice (8) et ladite capacité électrostatique C1 étant la capacité électrostatique entre ladite électrode pelliculaire conductrice (8) et ledit revêtement conducteur intérieur (13) et ladite tension impulsionnelle inverse générée V1 satisfaisant la relation (V0 x C0) > (V1 x C1).
  3. Unité d'affichage à tube cathodique selon la revendication 1 ou 2, comprenant en outre:
    un moyen (28) pour générer une deuxième tension impulsionnelle inverse V3 à polarité inversée par rapport à celle de composantes de courant alternatif générées à une borne de sortie dudit moyen formant transformateur de haute tension;
    un moyen (28, 32) servant à additionner l'une avec l'autre ladite tension impulsionnelle inverse V1 et ladite deuxième tension impulsionnelle inverse V3; et
    un moyen pour appliquer la tension de sortie dudit moyen d'addition (28, 32) audit revêtement conducteur intérieur (13) par l'intermédiaire de ladite capacité électrostatique (25, 8).
  4. Unité d'affichage à tube cathodique selon la revendication 3, dans laquelle la relation (V0 x C0) > ((V1 + V3) x C1) est satisfaite.
  5. Unité d'affichage à tube cathodique selon la revendication 1, dans laquelle ledit moyen pour générer une tension impulsionnelle inverse comprend un moyen pour obtenir une tension impulsionnelle inverse à partir d'un enroulement auxiliaire (64) disposé sur un noyau dudit collier de déviation (6).
  6. Unité d'affichage à tube cathodique selon la revendication 1, dans laquelle ledit moyen pour appliquer une tension impulsionnelle inverse comprend un moyen pour appliquer ladite tension impulsionnelle inverse par l'intermédiaire d'un condensateur (25) connecté, à une extrémité de celui-ci, à une borne de sortie d'un moyen formant transformateur (20) de haute tension.
  7. Unité d'affichage à tube cathodique selon la revendication 1, dans laquelle ledit moyen pour appliquer une tension impulsionnelle inverse comprend un moyen (Figure 18) servant à appliquer ladite tension impulsionnelle inverse par l'intermédiaire d'un condensateur (94) couplé, à une extrémité de celui-ci, à une partie formant bouton (90) d'anode afin d'acheminer une haute tension depuis un moyen formant transformateur (20) de haute tension jusqu'à une anode d'un tube cathodique (1).
  8. Unité d'affichage à tube cathodique selon la revendication 1, dans laquelle ledit moyen pour appliquer une tension impulsionnelle inverse comprend un moyen (Figure 19) pour appliquer ladite tension impulsionnelle inverse par l'intermédiaire d'un conducteur (96) disposé de manière coaxiale autour d'un câble (91) d'anode pour acheminer une haute tension depuis un moyen formant transformateur (20) de haute tension jusqu'à une anode d'un tube cathodique (1).
  9. Unité d'affichage à tube cathodique selon la revendication 1, dans laquelle ladite capacité électrostatique est établie par un condensateur (25) à capacité C1, et
    ledit moyen pour générer une tension impulsionnelle inverse (20, 64, 30, 40, 28, 32) génère une tension impulsionnelle inverse V1 qui satisfait la relation (V0 x C0) > (V1 x C1).
  10. Unité d'affichage à tube cathodique selon la revendication 1, dans laquelle une constante K présente dans une expression relationnelle K x V0 x C0 = V1 x C1 est comprise entre 0,1 et 0,9.
  11. Unité d'affichage à tube cathodique selon la revendication 1, dans laquelle l'épaisseur du verre dans une partie en regard de ladite bobine de déviation horizontale est plus forte que dans d'autres parties vers l'intérieur du tube cathodique (1), ce par quoi on cherche à réduire ladite capacité électrostatique C0.
  12. Unité d'affichage à tube cathodique selon la revendication 1, dans laquelle ledit revêtement conducteur intérieur (13) est formé de façon que ledit revêtement conducteur intérieur (13) ne soit pas formé dans une zone prédéterminée d'une partie en regard de ladite bobine de déviation horizontale, ce par quoi on cherche à réduire ladite capacité électrostatique C0.
  13. Unité d'affichage à tube cathodique selon la revendication 1, dans laquelle une constante diélectrique d'une matière constituée par du verre d'une partie en regard de ladite bobine de déviation horizontale est établie à 8 ou moins, ce par quoi on cherche à réduire ladite capacité électrostatique C0.
  14. Unité d'affichage à tube cathodique selon la revendication 2, dans laquelle 0,5 ≤ (C1/C0) ≤ 15.
  15. Unité d'affichage à tube cathodique selon la revendication 1, comprenant en outre un revêtement conducteur transparent (10) formé sur une surface externe d'un écran dudit tube cathodique (1) et relié à la terre.
  16. Unité d'affichage à tube cathodique selon la revendication 15, dans laquelle ledit revêtement conducteur transparent (10) comprend une résistance ayant une valeur de résistance par unité de surface de 2 x 106 [Ω/carré] ou moins.
  17. Unité d'affichage à tube cathodique selon la revendication 1, dans laquelle ledit moyen (20, 64, 30, 40, 28, 32) pour générer la tension impulsionnelle inverse V1 comprend un moyen pour obtenir une tension impulsionnelle inverse à partir d'un enroulement auxiliaire (64) disposé sur un noyau dudit collier de déviation (6).
  18. Unité d'affichage à tube cathodique selon la revendication 1, dans laquelle ledit moyen (20, 64, 30, 40, 28, 32) pour générer la tension impulsionnelle inverse V1 comprend:
    un moyen (64) servant à détecter une impulsion de retour-ligne générée dans ladite bobine de déviation horizontale; et
    un moyen (Figure 10) servant à atténuer et inverser ladite impulsion de retour-ligne détectée afin d'obtenir la tension impulsionnelle inverse V1.
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
JP25320894 1994-10-19
JP253208/94 1994-10-19
JP25320894A JP3218887B2 (ja) 1994-10-19 1994-10-19 陰極線管表示装置
JP303808/94 1994-12-07
JP30380894 1994-12-07
JP6303808A JPH08163474A (ja) 1994-12-07 1994-12-07 陰極線管表示装置

Publications (2)

Publication Number Publication Date
EP0708474A1 EP0708474A1 (fr) 1996-04-24
EP0708474B1 true 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)

Cited By (1)

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DE102011086646A1 (de) 2011-11-18 2013-05-23 Siemens Aktiengesellschaft Bildschirm und Verfahren zur Ansteuerung eines Bildschirms

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KR100190160B1 (ko) * 1995-10-27 1999-06-01 윤종용 디스플레이 기기의 전계 차폐 회로
JPH09153334A (ja) * 1995-11-29 1997-06-10 Mitsubishi Electric Corp 陰極線管装置及びその製造方法
JP2888421B2 (ja) * 1996-01-18 1999-05-10 株式会社日立メディアエレクトロニクス ディスプレイモニタ
JPH1092344A (ja) * 1996-07-25 1998-04-10 Toshiba Corp 陰極線管及び陰極線管装置
CN101002110B (zh) 2004-08-10 2010-12-08 佳能株式会社 放射线探测装置、闪烁体板及其制造方法和放射线探测系统
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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FI90598C (fi) * 1991-02-07 1994-02-25 Nokia Display Products Oy Menetelmä ja kytkentä katodisädeputken aiheuttaman haitallisen säteilyn pienentämiseksi
SE469456B (sv) * 1991-11-22 1993-07-05 Nokia Data Ab Foerfarande och anordning i en bildskaermsenhet foer att reducera elektriska vaexelfaelt i enhetens omgivning
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 (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102011086646A1 (de) 2011-11-18 2013-05-23 Siemens Aktiengesellschaft Bildschirm und Verfahren zur Ansteuerung eines Bildschirms
DE102011086646B4 (de) * 2011-11-18 2013-06-27 Siemens Aktiengesellschaft Bildschirm und Verfahren zur Ansteuerung eines Bildschirms

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DE69518713D1 (de) 2000-10-12
KR100204724B1 (ko) 1999-06-15
DE69518713T2 (de) 2001-05-31
EP0708474A1 (fr) 1996-04-24
TW395550U (en) 2000-06-21

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