Electric lamp and discharge devices – Cathode ray tube – Envelope
Reexamination Certificate
1999-06-25
2001-09-11
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
Cathode ray tube
Envelope
C445S043000, C445S072000
Reexamination Certificate
active
06288484
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to improvement in electrical insulation of electrodes called stem pins, provided for supplying/receiving electric signals, of a cathode-ray tube.
With the tendency to increase a voltage applied to stem pins of an electron gun for improving the performance of a color cathode-ray tube, a stem portion of the cathode-ray tube has been insulated by coating the stem portion with a room temperature curing type silicon resin. The room temperature curing type silicon resin, however, is disadvantageous in that it entraps bubbles when being cured. To solve degradation of insulation due to the bubbles, an electrical insulator used for insulation of a stem portion of a cathode-ray tube, and a cathode-ray tube provided with the electrical insulator for improving the insulation of a stem portion have been disclosed in Japanese Patent Laid-open Nos. Hei 7-94100 and Hei 8-111191.
According to the invention disclosed in Japanese Patent Laid-open No. Hei 7-94100, a cathode-ray tube with the improved insulation is manufactured by a manner of preparing a flat electrical insulator made from a silicon compound, punching the electrical insulator with a forming die to form holes in which stem pins and a stem tip are to be inserted, sticking the electrical insulator on a stem base, mounting the stem base thus stuck with the electrical insulator on a stem of the cathode-ray tube, and heating the cathode-ray tube to ensure the adhesive strength of the electrical insulator to the stem base.
According to the invention disclosed in Japanese Patent Laid-open No. Hei 8-111191, a cathode-ray tube is manufactured by a manner of extruding a thermosetting adhesive type silicon rubber composition into a tape, punching the tape into a half-cut shape using a die set to form holes in which stem pins required to be insulated when high voltages are applied thereto and a stem tip are to be inserted, sticking the electrical insulator tape on a stem base in such a manner as to be caught between a tip containing portion of the stem base and the stem tip, and mounting the stem base thus stuck with the electrical insulator tape on a stem of the cathode-ray tube, thereby improving the insulation between the stem pins to which high voltages are applied.
In the inventions disclosed in Japanese Patent Laid-open Nos. Hei 7-94100 and Hei 8-111191, the electrical insulator formed into the flat or tape shape is punched using a forming die or die set, and accordingly a surface to be brought into contact with the stem of the electrical insulator is formed into a smooth plane.
As a result, in both the inventions, when the stem base stuck with the electrical insulator is mounted on the stem, air may be entrapped between the smooth surface of the electrical insulator and the surface of the stem, and if gaps formed by the entrapped air are present between the stem pins required to be insulated, there may occur a problem in generating discharge due to degradation of insulation of the stem portion of the cathode-ray tube.
SUMMARY OF THE INVENTION
The present invention has been made to solve the above problem, and a first object of the present invention is to provide an electrical insulator capable of preventing entrapment of air between the surface of the electrical insulator stuck on a stem base and the surface of a stem.
A second object of the present invention is to provide a cathode-ray tube in which the above electrical insulator is mounted between a stem and a stem base of the cathode-ray tube, thereby improving the insulation between stem pins.
To achieve the first object, according to a first aspect of the present invention, there is provided an electrical insulator, which is provided between a stem of w a cathode-ray tube of an electron gun and a stem base mounted to the stem, for insulating stem pins erected on the stem from each other, the electrical insulator including: a fixed portion held between the stem and the stem base; and a projecting portion to be caught in a tip-containing portion of the stem base, the projecting portion being formed integrally with the fixed portion; wherein the fixed portion is provided with pin-containing portions for containing the stem pins to be insulated by forming notches in the fixed portion on the outer edge side.
An upper surface of the fixed portion is preferably formed into such a shape as to be brought substantially into line-contact with the stem when the stem base stuck with the electrical insulator is mounted to the stem.
Each of the pin containing portions opened outwardly, which are formed in the fixed portion, is preferably shaped such that a gap on the outer edge side is larger than that on the innermost side.
With this configuration, at the initial stage of contact of the fixed portion of the electrical insulator with the surface of the stem, the fixed portion is brought substantially into line-contact with the surface of the stem, so that it is possible to prevent entrapment between the fixed portion and the surface of the stem. Also, as the stem base is gradually pressed on the stem, the contact surface of the fixed portion with the glass surface of the stem is gradually enlarged, and in this case, since air pushed out by the enlarged contact surface is directed toward the outer edge side of the fixed portion on which the notches as the pin-containing portion are formed, it is possible to certainly prevent entrapment of air between the fixed portion and the surface of the stem. Further, since the pin containing portion is shaped such that the gap on the outer edge side is larger than that on the innermost side, air on the innermost side is liable to be discharged to the outer edge side, with a result that it is possible to more certainly prevent entrapment between the fixed portion and the surface of the stem.
To achieve the second object, according to a second aspect of the present invention, there is provided a cathode-ray tube including: an electrical insulator mounted between a stem and a stem base of an electron gun, the electrical insulator including a fixed portion and a projecting portion formed integrally with the fixed portion; wherein the fixed portion is held between the stem and the stem base in such a manner that stem pins erected on the stem are contained in pin containing portions formed in the fixed portion; and the projecting portion is caught between a tip of the stem and a tip containing portion of the stem base.
With this configuration, it is possible to ensure insulation between the stem pins required to be insulated by the fixed portion, and to ensure the adhesiveness between the stem tip and the tip-containing portion of the stem base by the projecting portion.
REFERENCES:
patent: 3867670 (1975-02-01), Schor et al.
patent: 5990610 (1999-11-01), Matsumoto et al.
patent: 2 537 339 (1998-06-01), None
patent: 7-94100 (1995-04-01), None
patent: 8-111191 (1996-04-01), None
Kanno Hirokazu
Setsuda Takashi
Berck Ken A
Kananen Ronald P.
Patel Vip
Rader Fishman & Grauer
Sony Corporation
LandOfFree
Electrical insulator and cathode-ray tube provided with the... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electrical insulator and cathode-ray tube provided with the..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electrical insulator and cathode-ray tube provided with the... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2528029