Deflection yoke of braun tube and method for fabricating...

Electric lamp and discharge devices – Cathode ray tube – Beam deflecting means

Reexamination Certificate

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C313S431000

Reexamination Certificate

active

06563259

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a deflection yoke (DY) of Braun tube, and more particularly, to a deflection yoke of Braun tube having an auxiliary coil which is capable of preventing a back electromotive force according to a main magnetic field even though the auxiliary coil is disposed at a portion where a main coil of a deflection yoke is disposed, to thereby complement characteristics of the main coil, and a method for fabricating an auxiliary coil of the deflection yoke.
2. Description of the Background Art
FIG. 1
shows a side view of a general Braun tube in accordance with a conventional art.
As shown in the drawing, Braun tube
1
includes a screen
3
on which an electron beam
10
radiated from an electron gun
2
is reproduced as a picture, and a deflection yoke
20
for deflecting the electron beam
10
coming from the electron gun
2
onto a corresponding fluorescent surface of the screen
3
.
FIG. 2A
is a side view of a saddle-saddle type deflection yoke and
FIG. 2B
is a plan view of the saddle-saddle type deflection yoke viewed from its opening side.
As shown in
FIG. 2A
, the saddle-saddle type deflection yoke
20
for Braun tube includes a horizontal deflection coil
21
for horizontal deflection, a vertical deflection coil
22
for vertical deflection, a ferrite core
23
for complementing a magnetic force generated by the current flowing to the horizontal deflection coil
21
and the vertical deflection coil
22
and improving a deflection efficiency; a holder
24
for mechanically determining relative positions of the horizontal deflection coil
21
, the vertical deflection coil
22
and the ferrite core
23
and mechanically fixing and combining them; a convergence yoke (or, called comma-free coil) typically disposed at a neck portion
29
of the holder
24
for improving a comma aberration generated by a vertical barrel type magnetic field; a ring band
26
disposed at the end of the neck portion of the holder
24
for mechanically combining the Braun tube
1
and the deflection yoke
20
; and a magnet
27
typically disposed at the end of an opening
28
of the deflection yoke
20
for correcting a raster distortion appearing at the upper end portion and a lower end portion of the screen.
Thusly constructed deflection yoke
20
of the Braun tube generates a deflection magnetic field as current having a predetermined wave form is applied to the horizontal deflection coil
21
and the vertical deflection coil
22
. In this respect, generally, the distribution of each deflection coil is adjusted in the lengthy direction, so that the red, green and blue electron beams
10
starting from different points can be converged to the same point on the screen and the outermost angle raster form (refer to reference numeral
61
of
FIG. 8
) can make a straight line with a predetermined size.
A signal in synchronization with the horizontal and vertical deflection current may flow to the convergence yoke
25
, so as to complement characteristics that is not enough to complete convergence by merely adjusting the distribution in the lengthy direction of the horizontal deflection coil
21
and the vertical deflection coil
22
.
Failure of converging the red, green and blue electron beams
10
to one point on the screen is called misconvergence (refer to reference numeral
62
of FIG.
8
). Conventionally, the misconvergence has been complemented in a manner that a convergence yoke
25
is usually installed at the neck portion
29
of the deflection yoke, the starting point of the electron beams
10
to thereby complement the initial position.
However, such method is limitedly adopted due to the following technical limitations.
First, in case of using the horizontal deflection current, the inductance is not possibly generated by above a predetermined level only with the use of the convergence yoke
25
, so that it is not applicable to a high frequency-adopted Braun tube. Thus, due to the limitation factor that the inductance is to be generated by below a predetermined level, its application is not easy in general cases where an additional circuit is not employed.
Secondly, in case of using the convergence yoke
25
, the length of a magnetic pole in use for the convergence yoke
25
is to be adjusted to the length limited in a neck portion. Thus, in order to have an effect at a favorable level, the number of turns of a coil should be increased to set an inductance value very high. However, due to the limitation to the space, winding of coil is limited, and thus, it is very difficult to lower a resistance. Accordingly, in case of using the vertical deflection current, there is a limitation for application.
Thirdly, as shown in
FIGS. 5A and 5B
, a ferrite core winding auxiliary coil
65
is installed at the position of the main deflection coil, not at the position of the convergence yoke
25
. In this case, however, the auxiliary coil
65
interacts with the magnetic field mostly formed by the horizontal deflection coil
21
, so that if a protective circuit is not provided therefor, the horizontal deflection magnetic field is much damaged, causing a difficulty in implementing a desired characteristic. In addition its application incurs much expense.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a deflection yoke of Braun tube having an auxiliary coil which are capable of complementing misconvergence of a deflection yoke of Braun tube without using an additional circuit and capable of reducing power consumption.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a deflection yoke of Braun tube having a horizontal deflection coil for horizontally deflecting electron beams radiated from an electron gun, a vertical deflection coil for vertically deflecting the electron beams, and a holder inserted between the horizontal and the vertical deflection coils for mechanically fixing them and electrically insulating them, including: an auxiliary coil having a first deflection portion coil extendedly formed from a ‘3-o'clock’ position at a neck side to a ‘3-o'clock’ direction of a screen side on the basis of the lengthy direction of the deflection coil; a first flange coil extendedly formed for a predetermined length from a ‘3-o'clock’ position at the screen side to a ‘12-o'clock’ direction of the screen side; a second deflection portion coil extendedly formed for a predetermined length from a ‘12-o'clock’ position at the screen side to a ‘12-o'clock’ direction of the neck side; a second flange coil extendedly formed for a predetermined length from a ‘12-o'clock’ position at the neck side to a ‘9-o'clock’ direction of the neck side; a third deflection portion coil extendedly formed for a predetermined length from a ‘9-o'clock’ position at the neck side to a ‘9-o'clock’ direction of the screen side; a third flange coil extendedly formed from a ‘9-o'clock’ position at the screen side to a ‘6-o'clock’ direction of the screen side; a fourth deflection portion coil extendedly formed for a predetermined length from a ‘6-o'clock’ position at the screen side to a ‘6-o'clock’ direction of the neck side; and a fourth flange coil extendedly formed from a ‘6-o'clock’ position at the neck side to a ‘3-o'clock’ direction of the neck side.
The auxiliary coil of the deflection yoke of Braun tube of the present invention is preferably installed at the holder of the deflection yoke.
The auxiliary coil of the deflection yoke of Braun tube of the present invention is preferably installed at a neck side of the deflection yoke.
To the auxiliary coil of the deflection yoke of Braun tube of the present invention, current in synchronization with a vertical deflection current is preferably applied.
To the auxiliary coil of the deflection yoke of Braun tube of the present invention, current in synchronization with a horizontal defle

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