Electric lamp and discharge devices: systems – Cathode ray tube circuits – Combined cathode ray tube and circuit element structure
Reexamination Certificate
2000-03-09
2001-09-25
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Cathode ray tube circuits
Combined cathode ray tube and circuit element structure
C313S402000, C313S409000, C313S467000
Reexamination Certificate
active
06294872
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a cathode ray tube for image display and, more particularly, to a cathode ray tube having a voltage-dividing resistor provided in an electron gun housed in its neck portion.
A cathode ray tube for image display has an electron gun for emitting plural electron beams, which electron gun is housed at one end of an evacuated envelope, and a phosphor screen (screen image plane) is formed by coating the internal surface of the other end of the evacuated envelope with a plural-color phosphor layer. Many color cathode ray tubes are also provided with a color selection electrode (for example, a shadow mask) disposed in proximity to the phosphor screen. The main trend in electron guns is a so-called in-line type electron gun which emits three electron beams in parallel with one another in one plane.
FIG. 14
is a perspective view illustrating the construction of a terminal portion of a voltage-dividing resistor
50
of the type installed in an electron gun.
FIG. 15
is a partial view illustrating the construction of a terminal portion of this resistor. The voltage-dividing resistor
50
has a resistor layer
22
having a predetermined resistance characteristic, the resistor layer
22
being formed on an insulating substrate
16
. An insulating glass coating layer
17
is formed to cover the resistor layer
22
(or resistor pattern). A terminal
53
at one end of the voltage-dividing resistor
50
is connected to a shield cup fixed to a sixth grid electrode, a terminal
51
at the other end of the voltage-dividing resistor
50
is connected to an electrode portion held at a ground potential, and a terminal
52
provided in the middle of the voltage-dividing resistor
50
is connected to an intermediate electrode.
As shown in
FIG. 15
, the terminal
51
is fixed to the insulating substrate
16
in such a way that a metallic eyelet
511
is caulked to the substrate
16
in the state where the terminal
51
is inserted in a terminal-receiving hole
15
, which is a through-hole provided in the substrate
16
, and is maintained in contact with a terminal-connecting electrode
14
. A connecting portion
51
C is formed integrally with the terminal
51
.
FIG. 16
is a cross-sectional view of the vicinity of the terminal
51
. In the prior art built-in resistor (voltage-dividing resistor), the whole of an electrode-side flange portion
51
A is maintained in contact with the terminal-connecting electrode
14
so that the terminal
51
and the terminal-connecting electrode
14
are reliably maintained in contact with each other. In addition, to reliably secure the terminal
51
to the insulating substrate
16
, a substrate-side flange portion
51
D is constructed so that its edge portion faces outward with respect to the terminal-receiving hole
15
. A color cathode ray tube provided with this kind of voltage-dividing resistor is disclosed in, for example, Japanese Utility Model Laid-Open No. 38484/1980.
Built-in resistors for cathode ray tubes of the type which have terminals fixed to an insulating substrate by caulking are disclosed in Japanese Patent Laid-Open Nos. 258680/1993, 68811/1994, 251901/1994, 260119/1997 and 298037/1997.
The metallic eyelet formed of a hard metal material, such as stainless steel, has the problem that it cannot be caulked to a sufficient extent, so that no stable electrical contact is established between the terminal and the conductive layer. To cope with this problem, the load during caulking may be made large. However, if the caulking load is excessively large, the opening edge of the through-hole of the insulating substrate will be damaged. In addition, the related art has the problem that the built-in resistor uses a large number of components and needs a complicated component management and manufacturing process.
BRIEF SUMMARY OF THE INVENTION
The invention solves the problems of the above-described related art and provides a color cathode ray tube having an electron gun provided with a voltage-dividing resistor having, a stable and good voltage supplying function.
According to the invention, an eyelet made of metal which constitutes a terminal for a voltage-dividing resistor has a flange portion having a surface on which a convex portion is formed, the surface being disposed on a side where the flange portion makes contact with a conductive film, and reliable electrical contact is established between the terminal and the conductive film formed on a substrate by the elasticity of the terminal. The end portion of the other side of the metal eyelet faces inward.
According to this construction, damage to the opening edge of a through-hole of an insulating substrate is prevented and the contact of the terminal with a terminal-connecting conductive film is improved. In addition, the difference in thermal expansion between the insulating substrate and the terminal due to a variation in temperature is absorbed by a concave portion of the flange portion, whereby the characteristics of the electrical connection are improved and the supply of a stable focus voltage is maintained, so that a highly reliable color cathode ray tube is obtained.
REFERENCES:
patent: 4672269 (1987-06-01), Kamohara
patent: 4786842 (1988-11-01), Shimoma et al.
patent: 5077497 (1991-12-01), Kamohara et al.
patent: 5416379 (1995-05-01), Inoue et al.
patent: 5-258680 (1993-10-01), None
patent: 6-68811 (1994-03-01), None
patent: 6-251901 (1994-09-01), None
patent: 9-260119 (1997-10-01), None
patent: 9-298037 (1997-11-01), None
Ishii Sakae
Miyamoto Satoru
Nakamura Hisao
Tsuruoka Atsushi
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
Tran Thuy Vinh
Wong Don
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