Electric lamp and discharge devices – Cathode ray tube – Envelope
Reexamination Certificate
1998-07-23
2002-03-26
Day, Michael H. (Department: 2879)
Electric lamp and discharge devices
Cathode ray tube
Envelope
C313S4770HC, C445S045000, C065S138000
Reexamination Certificate
active
06362564
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a color cathode ray tube. More particularly, it relates to a color cathode ray tube having a slim neck portion and a stem with an electron gun optimally joined to the neck portion.
2. Discussion of Related Art
Generally, a cathode ray tube of
FIG. 1
includes a fluorescent layer
20
, a panel
10
having a shadow mask
30
spaced a given distance away from fluorescent layer
20
, a funnel
40
having a slim neck portion
40
a
at the rear and secured to panel
10
, an electron gun
50
housed in the neck portion
40
a
and emitting an electron beam
70
to the fluorescent layer
20
, and a stem
60
sealed to neck portion
40
a
and executing the exhaust stroke through an exhaust pipe
60
a
provided to the stem
60
.
There is a deflection yoke
80
on the outer circumference of neck portion
40
a
of the cathode ray tube for deflecting an electron beam
70
emitted from electron gun
50
. When a heater in a cathode (not shown) on stem
60
of electron gun
50
emits, an oxide compound, applied to the upper surface of a cathode, emits electrons. The electrons emitted from the oxide compound of the cathode pass through the respective electrodes and form an electron beam
70
of required characteristics. The electron beam
70
is deflected by a magnetic field created by deflection yoke
80
, and passes through shadow mask
30
and hits on fluorescent layer
20
applied to the inside of panel
10
so that fluorescent layer
20
emits light to represent an image.
The cathode ray tube maintains a vacuum condition to smoothly perform the above operation, and stem
60
with a plurality of stem pins
90
for supplying power to electron gun
50
and exhaust pipe
60
a
for exhaust is assembled to neck portion
40
a.
The interior of the cathode ray tube is evacuated via exhaust pipe
60
a,
and thereafter exhaust pipe
60
a
is melted and sealed to maintain a vacuum condition.
The smaller the diameter of neck portion
40
a
becomes, the smaller the electric current that flows across the coil constituting deflection yoke
80
. The deflection yoke
80
creates a magnetic field when electron gun
50
operates in order that the electron beam emitted from electron gun
50
's oxide compound approaches fluorescent layer
20
applied to panel
10
, Much research and developments have been made to minimize the diameter of neck portion
4
a,
but there is a limit to the amount of diameter reduction of a neck portion
40
a.
First, as the diameter of neck portion
40
a
is reduced, the resolution of the electron gun is degraded yet, a high-performance electron gun of optimum design is desirable. Astigmatism that may occur by the deflection yoke by supplying focus voltages divided into two, thus compensating the resolution degradation around the screen peripheral part and optimizing a main lens. This enhances the uniformity of spots and assures high-performance of the electron gun. According to the techniques of dividing the focus voltage into two, the focus voltage is applied to a single stem pin to be divided into more than two voltages by a resistor mounted on the electron gun of the neck portion, and each focus voltage is applied through two focus voltage applying pins.
Second, as the diameter of neck portion
40
a
is reduced, the shape and size of the stem with metal pins for supplying one or two focus voltages and the required power to the electron gun need to be more precisely set, If not, a proper seal is not formed at the joint of stem
6
and neck portion
40
a.
Even if the seal is properly formed, cracks may form such that the interior of the cathode ray tube is not in a perfect vacuum state and causes poor internal voltage characteristics due to the improper sealing.
In stem
6
, metallic stem pins
9
are equidistantly disposed in a circular formation on the middle of stem
6
to provide the proper insulation, and the diameter of the circular information formed by the stem pins
9
is about 15.24 mm or 12.00 mm. A glass projection
6
b
is integrally formed with stem
6
around stem pins
9
in order to increase the strength and insulating characteristics the metallic stem pins
9
. When employing a slim neck portion
4
a,
stem
6
having a pin circle of 15.24 mm in diameter has a larger outer diameter than the neck portion
4
a
's inner diameter such that glass projection
6
b
comes in contact with neck portion
4
a
to cause cracking thereof or result in poor internal voltage characteristics.
Stem
6
having a circular information of 12.0 mm in diameter has an outer diameter that is much smaller than the inner diameter of neck portion
4
a
to this not form a proper seal. Even if the seal is formed; the sealed portion is too this, which is susceptible to cracking when forming a vacuum within the cathode ray tube.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a color cathode ray tube that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a cathode ray tube with a slim neck portion and a stem. Each having an optimum size for sealing.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the present invention provides a color cathode ray tube having a panel to which a fluorescent layer is applied, a slim neck portion receiving an electron gun therein, a funnel joined to the panel, and a stem with the electron gun sealed to the neck portion, wherein if an inner diameter of the neck portion and an outer diameter of the stem equal a and f, respectively, an interval between the neck portion's inner diameter a and the stem's outer circumference meets the condition of 0.2 mm≦(a−f)/2≦30.0 mm, and the neck portion's outer diameter equals 23.0 mm to 28.5 mm.
According to another aspect of the present invention, in a color cathode ray tube having a panel to which a fluorescent layer is applied, a slim neck portion with an electron gun, therein a funnel joined to the panel, and a stem with the electron gun sealed to the neck portion, if an inner diameter of the neck portion and an outer diameter of the stem equal a and f, respectively, an interval between the neck portion's inner diameter and the stem's outer circumference meets the condition of 0.85 a mm≦f ≦0.98 a mm.
According to still another aspect of the present invention, in a color cathode ray tube having a panel to which a fluorescent layer is applied, a slim neck portion with an electron gun, therein a funnel joined to the panel, and a stem with the electron gun sealed to the neck portion, if an outer diameter of the neck portion and a thickness of the neck portion equal b and t, respectively, they meet the condition of 0.08 b mm≦t≦0.1 b mm, and an outer diameter of the neck portion is 23.0 to 28.5 mm.
According to a further aspect of the present invention, in a color cathode ray tube having a panel to which a fluorescent layer is applied, a slim neck portion receiving an electron gun, therein, a funnel joined to the panel, and a stem with the electron gun sealed to the neck portion, if a thickness of the neck portion and a thickness of the stem equal t and T, respectively, they meet the condition of 0.8 tmm≦T≦1.4 tmm.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
REFERENCES:
patent: 4066310 (1978-01-01),
Day Michael H.
LG Electronics Inc.
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