Title: Color cathode-ray tube
Abstract: A rectangular-shaped deflection yoke, RTC (Round Core Tetra Coil Combined Deflection Yoke) enhances deflection sensitivity of a cathode-ray tube. More specifically, a deflection yoke structure for a cathode-ray tube is mounted with rectangular shaped deflection coils and circular shaped ferrite cores, and the difference between a maximum gap and a minimum gap for the deflection coil and the ferrite core is greatest at an end section on a screen side of the ferrite core.
Patent Number: 6,894,430 Issued on 05/17/2005 to Lee
| Inventors:
|
Lee; Seok Moon (Gumi-si, KR)
|
| Assignee:
|
LG. Philips Displays Korea Co., Ltd. (Gyeongsangbuk-do, KR)
|
| Appl. No.:
|
328016 |
| Filed:
|
December 26, 2002 |
Foreign Application Priority Data
| Jun 07, 2002[KR] | 2002-31941 |
| Current U.S. Class: |
313/440; 313/421 |
| Intern'l Class: |
H01J 029/70 |
| Field of Search: |
313/440,413,431,433,421,426
335/213,214
|
References Cited [Referenced By]
U.S. Patent Documents
| 3192432 | Jun., 1965 | Nero.
| |
| 3806750 | Apr., 1974 | Tsuneta et al.
| |
| 4229720 | Oct., 1980 | Heijnemans et al.
| |
| 5757120 | May., 1998 | Honda et al.
| |
| 5763995 | Jun., 1998 | Sano et al.
| |
| 6208068 | Mar., 2001 | Lee et al.
| |
| 6617780 | Sep., 2003 | Cho et al.
| |
| 6686709 | Feb., 2004 | Lee et al.
| |
| 2002/0008458 | Jan., 2002 | Akoh et al.
| |
| 2002/0027409 | Mar., 2002 | Kojima.
| |
| 2002/0140337 | Oct., 2002 | Kim et al.
| |
| 2003/0222566 | Dec., 2003 | Ogawa et al.
| |
| Foreign Patent Documents |
| 48-34349 | May., 1973 | JP.
| |
| 56-063757 | May., 1981 | JP.
| |
| 08-007792 | Jan., 1996 | JP.
| |
Primary Examiner: Zimmerman; Glenn
Attorney, Agent or Firm: Birch, Stewart, Kolasch & Birch, LLP
Claims
1. A color cathode-ray tube comprising a panel having a fluorescent screen, Red,
Green, and Blue fluorescent substances being applied to an inner surface of the
panel, a funnel coupled to a rear surface of the panel for maintaining an inside
thereof in a vacuum state, an electron gun installed inside of a pipe-shaped neck
section disposed at a rear side of the funnel for emitting electron beams, and
a deflection yoke for horizontally or vertically deflecting the electron beams,
wherein the deflection yoke comprises:
a horizontal deflection coil and a vertical deflection coil for deflecting electron
beams emitted from the electron gun in the horizontal or vertical direction;
a ferrite core for enhancing a magnetic efficiency by minimizing a loss in a
magnetic force generated by the horizontal and vertical deflection coils, wherein
a sectional configuration on a screen side of the horizontal or vertical deflection
coils has a substantially rectangular shape, and a shape of the ferrite core is
either circular or elliptical, and an outer surface dimension size (HS) of a flange
section of the horizontal defection coil on the screen side of the horizontal deflection
coil mounted inside of the ferrite core ranges from 80% of an inner face actual
size (FS) of an end section on the screen side of the ferrite core at the narrowest
portion of said flange section to no more than 110% of an inner face actual size
(FS) of an end section on the screen side of the ferrite core at the widest portion
of said flange section; and
a holder for fixing the horizontal and vertical deflection coils and the ferrite
core at predetermined positions and insulating the horizontal and vertical deflection
coils.
2. The color cathode-ray tube according to claim 1, wherein a sectional configuration
on a screen side of the horizontal and vertical deflection coils is in a substantially
rectangular shape.
3. The color cathode-ray tube according to claim 1, wherein a sectional configuration
on a screen side of the holder is in a substantially rectangular shape.
4. A color cathode-ray tube comprising a panel having a fluorescent screen, Red,
Green, and Blue fluorescent substances being applied to an inner surface of the
panel, a funnel coupled to a rear surface of the panel for maintaining an inside
thereof in a vacuum state, an electron gun installed inside of a pipe-shaped neck
section disposed at a rear side of the funnel for emitting electron beams, and
a deflection yoke for horizontally or vertically deflecting the electron beams,
wherein the deflection yoke comprises:
a horizontal deflection coil and a vertical deflection coil for deflecting electron
beams emitted from the electron gun in the horizontal or vertical direction;
a ferrite core for enhancing a magnetic efficiency by minimizing a loss in a
magnetic force generated by the horizontal and vertical deflection coils, wherein
a sectional configuration on a screen side of the horizontal or vertical deflection
coils has a substantially rectangular shape, and a shape of the ferrite core is
either circular or elliptical, and the outer surface perimeter of a flange section
on the screen side of the horizontal deflection coil mounted inside of the ferrite
core does not extend beyond the outer surface perimeter of an end section on the
screen side of the ferrite core; and
a holder for fixing the horizontal and vertical deflection coils and the ferrite
core at predetermined positions and insulating the horizontal and vertical deflection
coils.
5. The color cathode-ray tube according to claim 4, wherein a sectional configuration
on a screen side of the horizontal and vertical deflection coils is in a substantially
rectangular shape.
6. The color cathode-ray tube according to claim 4, wherein a sectional configuration
on a screen side of the holder is in a substantially rectangular shape.
7. A color cathode-ray tube comprising a panel having a fluorescent screen, Red,
Green, and Blue fluorescent substances being applied to an inner surface of the
panel, a funnel coupled to a rear surface of the panel for maintaining an inside
thereof in a vacuum state, an electron gun installed inside of a pipe-shaped neck
section disposed at a rear side of the funnel for emitting electron beams, and
a deflection yoke for horizontally or vertically deflecting the electron beams,
wherein the deflection yoke comprises:
a horizontal deflection coil and a vertical deflection coil for deflecting electron
beams emitted from the electron gun in the horizontal or vertical direction;
a ferrite core for enhancing a magnetic efficiency by minimizing a loss in a
magnetic force generated by the horizontal and vertical deflection coils, wherein
a sectional configuration on a screen side of the horizontal or vertical deflection
coils has a substantially rectangular shape, and that of the ferrite core is either
circular or elliptical, and the outer surface perimeter size of the flange section
on the screen side of the horizontal deflection coil mounted inside of the ferrite
core is within the inner surface boundary of an end section on the screen side
of the ferrite core; and
a holder for fixing the horizontal and vertical deflection coils and the ferrite
core at predetermined positions and insulating the horizontal and vertical deflection
coils.
8. The color cathode-ray tube according to claim 7, wherein a sectional configuration
on a screen side of the horizontal and vertical deflection coils is in a substantially
rectangular shape.
9. The color cathode-ray tube according to claim 7, wherein a sectional configuration
on a screen side of the holder is in a substantially rectangular shape.
10. The color cathode-ray tube according to claim 7, wherein a diameter of the
flange section on the screen side of the horizontal deflection coil mounted inside
of the ferrite core ranges from 80% to 100% of the diameter of the end section
on the screen side of the ferrite core.
11. A color cathode-ray tube comprising a panel having a fluorescent screen,
Red, Green, and Blue fluorescent substances being applied to an inner surface of
the panel, a funnel coupled to a rear surface of the panel for maintaining an inside
thereof in a vacuum state, an electron gun installed inside of a pipe-shaped neck
section disposed at a rear side of the funnel for emitting electron beams, and
a deflection yoke for horizontally or vertically deflecting the electron beams,
wherein the deflection yoke comprises:
a horizontal deflection coil and a vertical deflection coil for deflecting electron
beams emitted from the electron gun in the horizontal or vertical direction;
a ferrite core for enhancing a magnetic efficiency by minimizing a loss in a
magnetic force generated by the horizontal and vertical deflection coils, wherein
a sectional configuration on a screen side of the horizontal or vertical deflection
coils has a substantially rectangular shape, and that of the ferrite core is either
circular or elliptical, and a pair of the vertical deflection coils is arranged
on both sides of a vertical axis, and a length of a straight line (c) connecting
a horizontal axis to a point closest to the vertical axis in which an flange section
on the screen side of the vertical deflection coil and the outer surface of the
end section on the screen side of the ferrite core meet is shorter than a radius
(b) of the end section on the screen side of the ferrite core; and
a holder for fixing the horizontal and vertical deflection coils and the ferrite
core at predetermined positions and insulating the horizontal and vertical deflection
coils.
12. The color cathode-ray tube according to claim 11, wherein a sectional configuration
on a screen side of the horizontal and vertical deflection coils is in a substantially
rectangular shape.
13. The color cathode-ray tube according to claim 11, wherein a sectional configuration
on a screen side of the holder is in a substantially rectangular shape.
14. A color cathode-ray tube comprising a panel having a fluorescent screen,
Red, Green, and Blue fluorescent substances being applied to an inner surface of
the panel, a funnel coupled to a rear surface of the panel for maintaining an inside
thereof in a vacuum state, an electron gun installed inside of a pipe-shaped neck
section disposed at a rear side of the funnel for emitting electron beams, and
a deflection yoke for horizontally or vertically deflecting the electron beams,
wherein the deflection yoke comprises:
a horizontal deflection coil and a vertical deflection coil for deflecting electron
beams emitted from the electron gun in the horizontal or vertical direction;
a ferrite core for enhancing a magnetic efficiency by minimizing a loss in a
magnetic force generated by the horizontal and vertical deflection coils, wherein
a sectional configuration on a screen side of the horizontal or vertical deflection
coils has a substantially rectangular shape, and that of the ferrite core is either
circular or elliptical, and a pair of the vertical deflection coils is arranged
on both sides of a vertical axis, and a ratio of a radius (b) of the end section
on the screen side of the ferrite core to a length of a straight line (e) connecting
a horizontal axis to a vertical axis of a flange section on the screen side of
the vertical deflection coil in a region at an angle of 30° to 60° in
either direction with respect to the vertical axis, namely b/e, ranges from 0.7
to 1.1; and
a holder for fixing the horizontal and vertical deflection coils and the ferrite
core at predetermined positions and insulating the horizontal and vertical deflection
coils.
15. The color cathode-ray tube according to claim 14, wherein a sectional configuration
on a screen side of the horizontal and vertical deflection coils is in a substantially
rectangular shape.
16. The color cathode-ray tube according to claim 14, wherein a sectional configuration
on a screen side of the holder is in a substantially rectangular shape.
17. A color cathode-ray tube comprising a panel having a fluorescent screen,
Red, Green, and Blue fluorescent substances being applied to an inner surface of
the panel, a funnel coupled to a rear surface of the panel for maintaining an inside
thereof in a vacuum state, an electron gun installed inside of a pipe-shaped neck
section disposed at a rear side of the funnel for emitting electron beams, and
a deflection yoke for horizontally or vertically deflecting the electron beams,
wherein the deflection yoke comprises:
a horizontal deflection coil and a vertical deflection coil for deflecting electron
beams emitted from the electron gun in the horizontal or vertical direction;
a ferrite core for enhancing a magnetic efficiency by minimizing a loss in a
magnetic force generated by the horizontal and vertical deflection coils, wherein
a sectional configuration on a screen side of the horizontal or vertical deflection
coils has a substantially rectangular shape, and that of the ferrite core is either
circular or elliptical, and a pair of the vertical deflection coils is arranged
on both sides of a vertical axis, and a ratio of a distance L2 from the outer circumference
of the ferrite core to the farthest point of the flange section on the screen side
of the vertical deflection coil to a radius L1 of the ferrite core in a region
at an angle of 60° to 90° in either direction with respect to the vertical
axis, namely L2/L1, ranges from 0.05 to 0.13; and
a holder for fixing the horizontal and vertical deflection coils and the ferrite
core at predetermined positions and insulating the horizontal and vertical deflection
coils.
18. The color cathode-ray tube according to claim 17, wherein a sectional configuration
on a screen side of the horizontal and vertical deflection coils is in a substantially
rectangular shape.
19. The color cathode-ray tube according to claim 17, wherein a sectional configuration
on a screen side of the holder is in a substantially rectangular shape.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rectangular-shaped deflection yoke, RTC (Round
Core Tetra Coil Combined Deflection Yoke) for enhancing deflection sensitivity
of a color cathode-ray tube. More specifically, the present invention relates to
a deflection yoke structure for a color cathode-ray tube that is mounted with rectangular
shaped deflection coils and a circular shaped ferrite core, and a gap therebetween
is not uniform. Rather, the difference between a maximum gap and a minimum gap
is greatest at an end section on a screen side of the ferrite core.
2. Background of the Related Art
As depicted in FIG. 1, a color cathode-ray tube includes a panel
1 mounted
in a front surface of the cathode-ray tube, a fluorescent screen
3 placed
on an inner surface of the panel
1, three primary colors (chrominance signals),
namely R, G, and B, are being applied to the screen, a shadow mask
2 for
selecting a color incidented on the fluorescent screen
3, a funnel
6
coupled to a rear surface of the panel
1 for maintaining the inside of the
tube in a vacuum state, electron guns
5 mounted inside of a tube-shaped
neck portion on the rear side of the funnel
6 for emitting electron beams,
and a deflection yoke
4 that surrounds an outside of the funnel
6
and deflects the electron beams in the horizontal and vertical directions.
A generally known color cathode-ray tube uses a three-beam in-line type electron
gun. In such a cathode-ray tube, R, G, and B electron beams are arranged in parallel,
and a self-converging principle using non-homogenous (non-uniform) magnetic fields
is applied thereto for converging those three electron beams on one point of the
fluorescent screen
3.
Particularly, the deflection yoke
4, as illustrated in FIGS.
2
a and
2b, includes a pair of horizontal deflection coils
41 for deflecting electron beams emitted from the electron guns
5
in the horizontal direction, a pair of vertical deflection coils for deflecting
electron beams emitted from the electron guns
5 in the vertical direction,
a ferrite core
44 for enhancing a magnetic efficiency by minimizing a loss
in a magnetic force generated by the horizontal and vertical deflection coils,
a holder
43 for fixing the horizontal and vertical deflection coils and
the ferrite core at predetermined positions and insulating the horizontal and vertical
deflection coils, a COMA free coil
45 mounted in a neck portion of the holder
43 for improving comma aberration caused by a vertical barrel type magnetic
field, a ring band
46 mounted in an end of the neck portion of the holder
43 for mechanically coupling the cathode-ray tube with the deflection yoke
4, and a magnet
47 mounted in an end of an aperture side of the deflection
yoke
4 for correcting raster distortion (hereinafter, it is referred to
as distortion).
Thusly constituted deflection yoke
4 can be divided into several kinds,
as shown in Table 1, in accordance with a sectional configuration of an end portion
of the screen side of the horizontal, vertical deflection coils
41,
42
and the ferrite core
44.
That is, as depicted in FIGS. 4 and 5, if the horizontal and vertical deflection
coils
41,
42 have a circular shape, the sectional configuration of
the end portion of the screen side of the ferrite core
44 is also circular.
Similarly, if the horizontal and vertical deflection coils
41,
42
have a rectangular shape, the sectional configuration of the end portion of the
screen side of the ferrite core
44 is also rectangular.
| TABLE 1 |
| |
| |
Horizontal |
Vertical |
|
| Deflection |
deflection |
deflection |
Ferrite core |
| yoke |
coil |
coil |
| Circular deflection |
Circular |
Circular |
Circular core |
| yoke |
coil |
coil |
| RAC deflection |
Rectangular |
Rectangular |
Rectangular core |
| yoke |
coil |
coil |
| |
Especially, the RAC deflection yoke
4 has a more improved deflection
sensitivity than the circular deflection yoke
4 because the sectional configuration
of the end portion of the screen side for the horizontal and vertical deflection
coils
41,
42 and the ferrite core
44 in the RAC deflection
yoke
4 is a rectangular shape, respectively, and thus can shorten the distance
between electron beams.
In general, the conventional deflection yoke
4 allows a current having
a frequency of 15.75 KHz or above to travel in the horizontal deflection coil
41,
and using the magnetic field generated around the coil, deflects electron beams
inside of the cathode ray tube in the horizontal direction. Also, the conventional
deflection yoke
4 allows a current having a frequency of 60 Hz to travel
in the vertical deflection coil
42, and using the magnetic field generated
around the coil, deflects electron beams inside of the cathode ray tube in the
vertical direction.
One of recently developed deflection yokes is a self-convergence type deflection
yoke
4, which uses the non-uniform magnetic fields around the horizontal
and vertical deflection coils
41,
42 in order to converge three electron
beams on a screen, without using a separate additional circuit or device.
In other words, by adjusting the winding distribution of the horizontal and vertical
deflection coils
41,
42, the self-convergence type deflection yoke
4 creates a barrel or pin-cushion shaped magnetic field for each section
(i.e., aperture section, middle section, neck section), and allows three electron
beams to experience a different deflecting force from one another depending on
their positions, yet to converge upon one point from different distances although
each electron beam starts and ends in different positions from one another.
Meanwhile, when an attempt was made to generate a magnetic field by providing
a current to the deflection coil, it was discovered that it was not an easy task
to deflect electron beams to the entire surface of the screen using only the magnetic
field generated by the coil. To avoid such difficulties, many now use the ferrite
core
44 having a high permeability, hoping to minimize any loss in the magnetic
field on its way of return and consequently to enhance the magnetic efficiency
and magnetic force.
Referring to FIG. 7, each of the pair of horizontal deflection coil consists
of a rectangular-shaped upper horizontal deflection coil and a rectangular-shaped
lower horizontal deflection coil. The pin-cushion shaped horizontal deflection
magnetic field is created by connecting the upper and lower horizontal deflection
coils in parallel as illustrated in FIG. 3
a, and allowing a saw-tooth shaped
horizontally deflecting current to travel in the coils (see FIG. 3
b).
The deflection yoke with the constitution described above can be largely divided
into two groups.
One of them is associated with the circular deflection yoke
4 where the
horizontal and vertical deflection coils
41,
42 have a circular shape,
and the sectional configuration of the end portion of the screen side is also circular
as shown in FIGS. 4 and 5. In such case, the area ratio of an aperture section
of the neck side of the deflection coil to an aperture section on the screen side
of the deflection coil is not smaller than 10 to 1, meaning that the center of
the deflection slants toward the neck side.
In reality, though, the position of the deflection yoke mounted in the cathode
ray tube should be designed in such a manner that it inclines to the screen side,
not the neck side, in order to reserve a little allowance against BSN (Beam Strike
Neck) phenomenon, namely electron beams emitted from the electron guns strike the
inner surface of the funnel. This unfortunately weakens the deflection sensitivity
a great deal.
The other is associated with the RAC type deflection yoke
4 where the
configuration of the horizontal and vertical deflection coils
41,
42
and the ferrite core
44 are all rectangular. As depicted in FIGS. 6 and
7, three electron beams emitted from the electron guns
5, namely red, green,
and blue beams, pass through the horizontally deflected magnetic field, and according
to the Fleming's left hand rule the electron beams are deflected in the horizontal
direction, being inversely proportional to the cube of the distance between the
inner surface of the horizontal deflection coil and the electron beams.
Therefore, if the horizontal and vertical deflection coils
41,
42 have a rectangular shape, the distance between the electron beams and
the deflection coil becomes shorter by 20% and the horizontal and vertical deflection
sensitivities can be improved up to approximately 20˜30%.
To summarize, the conventional deflection yoke
4 for use in cathode ray
tube has the following shortcomings.
First, in case of the circular deflection yoke, its circular shaped deflection
coil creates an unnecessary distance between the electron beams and the deflection
coil as illustrated, and as the result thereof, the deflection sensitivity is worse.
In FIG. 10, ΔV is a vertical distance between the electron beams and the
deflection coil and ΔH is a horizontal distance between the electron beams
and the deflection coil. This problem becomes more serious for an wide angle deflection
yoke. Hence, it seems almost impossible to develop a high-resolution, high frequency
deflection yoke at this point.
Second, a percentage of contraction of the ferrite core
44 mounted
in RAC deflection yoke reaches 20%, and the process tolerance due to limitations
existing in a manufacturing process is ±2%. In addition, in case of the conventional
ferrite core
44, of which inner surface has a rectangular shape (despite
the original purpose of using the rectangular shaped inner surface, such as, enhancing
the deflection sensitivity) it gives rise to different diameters for the inner
surfaces on the upper and lower sides. In consequence, the process tolerance of
the manufacturing process was three times (in maximum) greater than that of the
conventional circular core, and the production yield of ferrite cores was at most
50% of the conventional circular cores. In fact, since the shape of the inner surface
of the rectangular ferrite core is also rectangular, conducting an abrasive blasting
process more effectively during the manufacturing process and therefore maintaining
precise size can be very difficult. This small quantity, 50% (at best), of rectangular
cores only increased the unit price of the core up to 200% of the conventional
circular core.
SUMMARY OF THE INVENTION
An object of the invention is to solve at least the above problems and/or disadvantages
and to provide at least the advantages described hereinafter.
Accordingly, one object of the present invention is to solve the foregoing
problems by providing a deflection yoke structure for the cathode-ray tube with
enhanced deflection sensitivity by using a RTC deflection yoke which cross-section
has a rectangular shape, the RTC deflection yoke including a rectangular shaped
deflection coil and a circular shaped ferrite core, wherein a difference between
a maximum gap and a minimum gap among other gaps between the deflection coil and
the ferrite core is greatest at an end portion of the screen side of the ferrite core.
Another object of the present invention to provide a deflection yoke for
the cathode-ray tube capable of reducing size distribution of an inner surface
thereof and easing an abrasive blasting process for thereby making a remarkable
improvement in yield and size distribution of ferrite cores.
The foregoing and other objects and advantages are realized by providing a color
cathode ray tube comprising a panel having a fluorescent screen on which Red, Green,
and Blue fluorescent substances are applied, a funnel coupled to a rear surface
of the panel for maintaining an inside thereof in a vacuum state, an electron gun
installed inside of a pipe-shaped neck section disposed at a rear side of the funnel
for emitting electron beams, and a deflection yoke for horizontally or vertically
deflecting the electron beams, wherein the deflection yoke comprises a horizontal
deflection coil and a vertical deflection coil for deflecting electron beams emitted
from the electron gun in the horizontal or vertical direction, a holder for fixing
the horizontal and vertical deflection coils and the ferrite core at predetermined
positions and insulating the horizontal and vertical deflection coils and a ferrite
core for enhancing a magnetic efficiency by minimizing a loss in a magnetic force
generated by the horizontal and vertical deflection coils. Preferably, the sectional
configuration of the screen side of the horizontal or vertical deflection coils
is rectangular in shape, and the shape of the ferrite core is either circular or
elliptical. Also, an outer surface size (HS) of a flange section on the screen
side of the horizontal deflection coil mounted inside of the ferrite core is in
a range of from 80% to 110% of an inner face actual size (FS) of an end section
on the screen side of the ferrite core.
According to another aspect of the invention, a color cathode ray tube
comprises a panel having a fluorescent screen on which Red, Green, and Blue fluorescent
substances are applied, a funnel coupled to a rear surface of the panel for maintaining
an inside thereof in a vacuum state, an electron gun installed inside of a pipe-shaped
neck section disposed at a rear side of the funnel for emitting electron beams,
and a deflection yoke for horizontally or vertically deflection the electron beams,
wherein the deflection yoke comprises a horizontal deflection coil and a vertical
deflection coil for deflecting electron beams emitted from the electron guns in
the horizontal or vertical direction, a ferrite core for enhancing a magnetic efficiency
by minimizing a loss in a magnetic force generated by the horizontal and vertical
deflection coils, and a holder for fixing the horizontal and vertical deflection
coils and the ferrite core at predetermined positions and insulating the horizontal
and vertical deflection coils. Preferably, the sectional configuration of the screen
side of the horizontal or vertical deflection coils has a rectangular shape, and
that of the ferrite core is either circular or elliptical.
According to the embodiment described above, the sectional configuration
of the neck side of the horizontal or vertical deflection coils is either circular
or elliptical.
Preferably, the sectional configurations of the screen side and the neck
side of the ferrite core are all circular or elliptical.
According to the embodiment described above, the deflection yoke can exist
even when few minimum and maximum gaps exist between the ferrite core and its corresponding
deflection coil, on the basis of a plane perpendicular to a tube axis.
Preferably, the difference between the maximum gap and the minimum gap
is greatest at the end portion of the screen side.
More preferably, the minimum gap ranges from 0 mm to 1.0 mm, and the maximum
gap ranges from 1 mm to 30 mm.
Additional advantages, objects, and features of the invention will be
set forth in part in the description which follows and in part will become apparent
to those having ordinary skill in the art upon examination of the following or
may be learned from practice of the invention. The objects and advantages of the
invention may be realized and attained as particularly pointed out in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described in detail with reference to the following drawings
in which like reference numerals refer to like elements wherein:
FIG. 1 is a schematic diagram of a cathode-ray tube and a deflection yoke from
a related art;
FIGS. 2
a and 2
b are schematic diagrams of a deflection
yoke from a related art;
FIGS. 3
a and 3
b, respectively, illustrates a horizontally
deflected circuit and a horizontally deflecting current applied to the deflection
yoke of the related art;
FIG. 4 is a cross-sectional view illustrating a circular deflection yoke from
a related art;
FIG. 5 is a perspective view illustrating the circular deflection yoke from
a related art;
FIG. 6 is a cross-sectional view illustrating a RAC deflection yoke from a related art;
FIG. 7 is a perspective view illustrating the RAC deflection yoke from the related art;
FIG. 8 is a cross-sectional view illustrating a RTC deflection yoke according
to a preferred embodiment of the present invention;
FIG. 9 is a perspective view illustrating the RTC deflection yoke according
to the preferred embodiment of the present invention;
FIG. 10 is a cross-sectional view of a funnel section of the cathode ray tube;
FIGS. 11
a and 11
b, respectively, represents before and
after a vertical deflection coil is assembled;
FIG. 12 is an assembly diagram of the vertical deflection coil of the present invention;
FIG. 13 is an assembly diagram of the vertical deflection coil and a ferrite
core of the present invention;
FIGS. 14
a through 14
c illustrate an arrangement of a screen
side flange end section of a horizontal deflection coil and a screen side end portion
of a ferrite core in a conventional circular deflection yoke, a conventional RAC
deflection yoke, and a RTC deflection yoke according to the present invention, respectively;
FIG. 15 is a cross-sectional view of the RTC deflection yoke according to the
present invention;
FIG. 16 is a view explaining a relation between a leakage magnetic field/deflection
power and HS/FS;
FIG. 17 is a view illustrating a structure of a general vertical deflection coil;
FIG. 18 diagrammatically represents a layout of the flange section on the screen
side and the end section on the screen side of the ferrite core of the conventional
circular deflection yoke;
FIG. 19 diagrammatically represents an arrangement of the flange section on
the screen side and the end section on the screen side of the ferrite core of the
RTC deflection yoke according to the present invention;
FIG. 20 is a graph explaining a relation between a deflection force and a length
of straight line (e) along a vertical axis of the screen side flange section of
the vertical deflection coil from a horizontal axis in a region at an angle of
30° to 60° from the vertical axis; and
FIG. 21 is a front view of the vertical deflection coil and the ferrite core
of the RTC deflection yoke according to the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The following detailed description will present a deflection yoke structure for
the cathode-ray tube according to a preferred embodiment of the invention in reference
to the accompanying drawings.
As depicted in FIGS. 8 and 9, the sectional configuration on the screen sides
of the horizontal and vertical deflection coils
41,
42 of the deflection
yoke
4 embodying the principles of the present invention, RTC (Round Core
Tetra Coil Combined) deflection yoke are in a substantially rectangular shape.
In addition, the sectional configuration on the screen side of the holder in
the
RTC deflection yoke is in a rectangular shape. The ferrite core
44 as shown
in FIGS. 8,
9,
12, and
13 is designed in such a manner that
there is a maximum gap and a minimum gap between the inner surface on the screen
side of the ferrite core and the deflection coil on opposite side.
The difference between the two gaps is greatest at the screen side end section
of the ferrite core
44. This is good for improving convergence and distortion
errors caused by the size deviation on the inner surface of the rectangular shaped
ferrite core
44. Further, the cost of materials for ferrite cores
44
can be reduced, and the deflection sensitivity can be greatly enhanced.
Similarly, according to the structure of the RTC deflection yoke shown
in FIGS. 8,
9,
11a,
11b,
12, and
13,
the screen sides of the horizontal and vertical deflection coils
41,
42
are in a rectangular shape, thereby improving the size deviation of the inner surface
of the ferrite core
44 and the deflection sensitivity, and the size of the
rectangular shape of the sectional end on the screen side of the ferrite core
44
is not large because it will only give rise to a severe size deviation as in the
related art, but the deflection yoke is structured in a particular way so that
the gap between the inner surface of the ferrite core and its opposite vertical
deflection coil
42 is sometimes largest or smallest on the basis of the
plane perpendicular to the tube axis.
In fact, the difference between the maximum gap and the minimum gap is greatest
at the end section on the screen side of the ferrite core
44.
The ferrite core
44, as shown in FIG. 8, has a structure in which, the
minimum gap is almost homogeneous within a range 0˜1 mm at the end section
on the screen side of the deflection coil, having used the perpendicular plane
to the tube axis as the basis, while the maximum gap between the vertical deflection
coil
42 and the inner surface of the ferrite core
44 is in range
of 1 mm˜30 mm.
Also as depicted in FIG. 13, the increase rate of the maximum gap toward the
tube axis of the cathode-ray tube, given that the neck side of the ferrite core
44 was used as the basis, ranges from 0% to 6000% to the most, and the rate
gradually increased from the neck side to the screen side end section of the ferrite
core
44.
Thusly structured RTC deflection yoke is distinctive from the other known
circular deflection yokes and RAC deflection yoke in the related art in many aspects.
To begin with, comparing the circular deflection yoke with the RAC deflection
yoke, one realizes that the deflection sensitivity of the deflection yoke is inversely
proportional to the cubic of the distance between the deflection coil and the electron
beam. Also, the rectangular deflection coil, unlike the circular deflection coil,
has shortened the distance between the deflection coil and the electron beam by
20%, and this consequently improved the deflection sensitivity by 20-30%.
However, the conventional RAC deflection yoke exposed several shortcomings.
For example, since the cross-section of the deflection coil and the ferrite core
were all in a rectangular shape, the inner surface of the ferrite core naturally
had different lengths. This size deviation eventually caused a mis-convergence
and distortion error, and an increase in cost. Hence, many had a very difficult
time producing this type of deflection yoke.
On the other hand, the RTC deflection yoke of the present invention is different
from the conventional circular deflection yoke in terms of the center of the deflection
of the horizontal deflection coil.
That is, the inner surface areas of aperture sections on the neck side for both
deflection yokes are similar to each other. However, in case of the circular deflection
yoke's aperture section on the neck side is and its aperture section from the middle
part to the screen side, each section being non-circular, the inner surface area
of the aperture section is at least 10 times greater than the inner surface area
of the aperture section on the neck side. On the other hand, the inner surface
area of the aperture section in the RTC deflection yoke is at least four times
greater than that of the neck side. This means that the center of the deflection
for the horizontal deflection coil for the RTC deflection coil, unlike the circular
deflection coil, is much closer to the screen side.
When the center of deflection translates toward the screen side, more space
is created, e.g., several millimeters broader than the conventional deflection
yoke, no matter how often the electron beams emitted from the electron gun might
strike the inner surface of the funnel. This phenomenon is called BSN (Beam Strike
Neck), and the horizontal deflection coil is shifted closer to the neck side by
1-10 mm.
The same result is obtained from the vertical deflection coil.
If the horizontal and vertical deflection coils translate toward the neck side,
the ferrite core should translate to the neck side also. The following explains
some of advantages of the RTC deflection yoke over the conventional circular deflection yoke.
First of all, when the horizontal and vertical deflection coils move to the
neck side, the magnetic flux density per unit area is increased, and the deflecting
force for deflecting electron beams gets stronger, and the deflection sensitivity
is greatly improved.
The above is an extra effect for the deflection sensitivity besides the enhanced
deflection density obtained from the change of configuration of the deflection
coil, namely from a circular shape to a rectangular shape.
In addition, the ferrite core of the present invention, unlike the conventional
circular deflection yoke, translates closer to the neck side by 1-10 mm, so the
cross-sectional configuration of the ferrite core gets smaller and the difference
between the neck side area and the screen side area is reduced. In its result,
the cost of materials for ferrite cores can be reduced.
When the RTC deflection yoke is compared with the conventional RAC deflection
yoke, it is found that the horizontal and vertical deflection coils and the holder
for both are all in a substantially rectangular shape, but the sectional configuration
on the screen side of the ferrite core in the RTC deflection yoke is a circular
shape while that of the conventional RAC deflection yoke is a rectangular shape.
In addition, the RTC deflection yoke and the RAC deflection yoke manifest similar
deflection sensitivities. The underlying principle of this is provided below.
The horizontal deflection sensitivity (Ph) can be defined as follows:
Here, Ph is the deflection sensitivity of the horizontal deflection coil; Lh
is an inductance of the horizontal deflection coil; Ihpeak-peak is a peak value-peak
value of the current traveling in the horizontal deflection coil. If the configuration
of the ferrite core changes from the rectangular shape to the circular shape, the
Ih value is increased but the inductance value (Lh) of the horizontal deflection
coil is decreased. Hence, this offsets the difference of the horizontal deflection
sensitivities for both deflection yokes.
The RTC deflection yoke according to the present invention is more advantageous
than the conventional RAC deflection yoke in that it can improve convergence and
distortion errors due to the size deviation on the inner surface of the rectangular
ferrite core
44 and reduce the cost of materials for the ferrite core.
Moreover, the ferrite core of the present invention, unlike the known rectangular
ferrite core illustrated in FIG. 8, is in a circular shape, so the inner surface
diameter in the horizontal and vertical directions is uniform. This makes it easier
to produce a fine-pitch ferrite core having a very high precision and the size
deviation of the inner surface below 0.02 mm through the abrasive blasting process.
Further, the yield of such ferrite cores becomes about three times greater than
that of the rectangular ferrite core in the related art.
FIGS. 14
a and
14b depict a layout of the flange section
on the screen side in the horizontal deflection coil and the end section on the
screen side of the ferrite core in the conventional circular and RAC deflection
yokes, respectively.
If the horizontal deflection coil is in a circular shape, the shape of ferrite
core
44 is also circular. Similarly, if the horizontal deflection coil has
a rectangular shape, the ferrite core
44 has the rectangular shape also.
Because the flange section
41-
3 on the screen side of the horizontal
deflection coil is spaced out of the screen side end of the ferrite core
44,
the loss in the magnetic force produced by the current flowing in the horizontal
and vertical deflection coils is reduced, and the ferrite core for improving the
deflection efficiency cannot have any influence thereon. Accordingly, leakage magnetic
field intensities increase.
As shown in FIG. 13, the RTC deflection yoke according to the present invention
is particularly structured so as to make the difference between the maximum gap
and the minimum gap described above is greatest at the end section of the screen
side of the ferrite core
44.
As well depicted in FIG. 14
c, the maximum gap exists on the basis of the
plane perpendicular to the horizontal deflection coil
41 and the tube axis
at the end section on the screen side of the ferrite core
44, and the flange
section
41-
3 on the screen side of the horizontal deflection coil
is formed on an inward side the ferrite core
44.
FIG. 15 is a cross-sectional view of the RTC deflection yoke according to the
present invention. The outer surface diameter (HS) of the flange section on the
screen side of the horizontal deflection coil ranges 80% to 110% of the inner surface
diameter (FS) on the screen side of the ferrite core. As its result, the leakage
magnetic field intensity and the deflection power were reduced.
More specifically speaking, as FIGS. 14
a and
14b represent,
the outer surface diameter (HS) of the flange section on the screen side of the
horizontal deflection coil is shorter than the outer or inner surface diameter
(FS) on the screen side of the ferrite core while the conventional flange section
on the screen side of the horizontal deflection coil used to be outside of the
ferrite core. In short, the flange section is located inside or outside end section
of the ferrite core for thereby reducing the leakage magnetic field intensity and
the deflection power more effectively.
Table 2 (provided below) shows the ratio (in percentage) of the outer surface
diameter (HS) of the flange section on the screen side end section of the horizontal
deflection coil to the inner surface diameter (FS) on the screen side of the ferrite
core in different models, such as, the conventional circular and RAC deflection
yokes and the RTC deflection yoke of the present invention.
| TABLE 2 |
| |
| |
Outer surface |
|
|
| |
diameter (HS) of the |
|
|
| |
flange section on the |
Inner surface |
|
| |
screen side of the |
diameter (FS) on the |
|
| |
horizontal deflection |
screen side of the |
HS/FS |
| Model |
coil |
ferrite core |
(%) |
| |
| |
| Circular DY (from |
140 mm |
110.21 mm |
127.0% |
| the related art) |
| RAC DY (from the |
100 mm |
83 mm |
120.5% |
| related art) |
| RTC DY (from the |
100 mm |
105.36 mm |
94.9% |
| present invention) |
| |
As shown in Table 2, the ratio (in percentage) of the outer surface diameter
(HS)
of the flange section on the screen side of the horizontal deflection coil to the
inner surface diameter (FS) on the screen side end section of the ferrite core
in the RTC deflection yoke according to the present invention, HS/FS, is below
100%. But HS/FS of the conventional deflection yoke is greater than 120%. In short,
since the ratio of HS/FS of the horizontal deflection coil is small, the deflection
yoke according to the present invention is capable of diminishing the leakage magnetic
field intensity and the deflection power more effectively.
Preferably, the outer surface diameter (HS) of the flange section on
the screen side of the horizontal deflection coil mounted inside of the ferrite
core
44 ranges from 80% to 110% of the inner surface diameter (FS) of the
end section on the screen side of the ferrite core.
More preferably, the outer surface diameter (HS) of the flange section on the
screen side of the horizontal deflection coil mounted inside of the ferrite core
44 ranges from 80% to 100% of the inner surface diameter (FS) of the end
section on the screen side of the ferrite core.
Meanwhile, the flange section
41-
3 on the screen side of
the horizontal deflection coil
41 has little influence on deflecting electron
beams, but it can deteriorate the deflection sensitivity in the horizontal direction
by increasing the inductance value of the horizontal deflection coil
41
too much. Therefore, if the flange section
41-
3 on the screen side
of the horizontal deflection coil can be made as small as possible, reducing invalid
magnetic fields, the deflection sensitivity can be greatly improved.
As illustrated in FIG. 17, the vertical deflection coil
42 consists of
a flange section
42-
1 on the neck side, a middle section
42-
2,
and a flange section on the screen side
42-
3. The middle section
42-
2 located to be parallel to the tube axis of the cathode-ray tube
substantially deflects electron beams in the vertical direction. The flange section
42-
1 on the neck side rarely deflects electron beams but increases
the inductance value of the deflection coil. Primarily, the flange section
42-
3
on the screen side and the flange section
42-
1 on the neck side has
the same function.
FIG. 18 diagrammatically represents a layout of the flange section on the screen
side and the end section on the screen side of the ferrite core of the conventional
circular deflection yoke.
Here, the vertical deflection coil
42 as well as the ferrite core
44
is in a circular shape. Also, the flange section
42-
3 on the screen
side of the vertical deflection coil surrounds the entire end section on the screen
side of the circular ferrite core
44, and most of the flange section
42-
3
on the screen side of the vertical deflection coil is located outside the ferrite
core
44. This consequently increases the vertical inductance to a great
extent, and the deflection sensitivity in the vertical direction gets worse.
As depicted in FIG. 19, a pair of vertical deflection coils
42 is arranged
on both sides of the vertical axis.
The distance (c) from the horizontal axis to a point closest to the vertical
axis in which the flange section
42-
3 on the screen side of the vertical
deflection coil and the outer surface of end section on the screen side of the
ferrite core
44 meet is shorter than the radius (b) of the end section on
the screen side of the ferrite core
44.
As shown in FIG. 19, the ratio of a radius (b) of the end section on the screen
side of the ferrite core to a length of a straight line (e) connecting a horizontal
axis to a vertical axis of the flange section
42-
3 on the screen
side of the vertical deflection coil in a region at an angle of 30° to 60°
from the vertical axis, i.e., b/e, ranges from 0.7 to 1.1.
FIG. 20 is a graph for explaining a relation between a deflection force and
a length of straight line (e) along a vertical axis of the screen side flange section
42-
3 of the vertical deflection coil from a horizontal axis in a
region at an angle of ±(30°˜60°) from the vertical axis. As
manifested in the drawing, the deflection power is proportional to the e value.
FIG. 21 is a front view of the vertical deflection coil
42 and the ferrite
core
44 of the RTC deflection yoke according to the present invention. Suppose
that the radiuses of the ferrite cores
44 using the horizontal axis as a
coordinate axis are L1 and L3, and the distance from the outer circumference of
the ferrite core
44 to the farthest parts of the flange section
42-
3
on the screen side of the vertical deflection coil are L2 and L4. Then, the smallest
L2/L1 on the basis of the horizontal axis was 0.05, and the biggest L4/L3 in the
region at an angle of -60° from the vertical axis was 0.13. In other words,
in the region at an angle of 60° to 90° from the vertical axis (in either
direction) 0° to 30° from the horizontal axis (in either direction),
the ratio of the distance L2, L4 from the outer circumference of the ferrite core
to the farthest point of the flange section on the screen side of the vertical
deflection coil to the radius L1, L3 of the ferrite core
44, i.e., L2/L1
or L4/L3, ranges from 0.05 to 0.13.
In conclusion, the RTC deflection yoke according to the present invention has
advantages as follows
First, because the inner surface of the RTC type ferrite core is a circular
shape, the size deviation in connection with the inner surface of the ferrite core
is reduced by more than ½, and it becomes easy to manufacture a ferrite core
with a high precision through the abrasive blasting process on the inner surface
of the ferrite core. Further, the cost of materials for the ferrite core can be
reduced down to ⅓, and the convergence and distortion errors often found
in the conventional deflection yoke are greatly improved for thereby realizing
a fine-pitch deflection yoke;
Second, the deflection coil according to the present invention, unlike the
conventional circular deflection yoke, has a rectangular shape, and the deflection
yoke can be shifted closer to the neck side by 1-10 mm. As the result thereof,
the deflection sensitivity is enhanced up to 20-30% of the deflection sensitivity
for the circular deflection yoke;
Third, the small sized flange section on the screen side of the horizontal
and vertical deflection coils mounted in the RTC deflection yoke according to the
present invention is effective for reducing the leakage magnetic field intensity
and the deflection power; and
Fourth, unlike the conventional RAC core, because the ferrite core according
to the present invention has a large air layer between the horizontal and vertical
deflection coils, the present invention can be advantageously used for improving
a heating effect due to the enhanced convection effect.
While the invention has been shown and described with reference to certain
preferred embodiments th
