Electric lamp and discharge devices: systems – Cathode ray tube circuits – Cathode-ray deflections circuits
Reexamination Certificate
2001-07-09
2003-10-07
Vu, David (Department: 2821)
Electric lamp and discharge devices: systems
Cathode ray tube circuits
Cathode-ray deflections circuits
C315S399000
Reexamination Certificate
active
06630802
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a color CRT (Cathode Ray Tube) integrated with deflection circuit, and more particularly, to a color CRT having a deflection circuit formed integrally with the color CRT for driving a deflection yoke mounted on the color CRT by previously removing the causes of fluctuation of the deflection yoke according to the change of set conditions, without mounting on a substrate having a video signal processor of a chassis.
2. Description of the Related Art
As shown in
FIG. 1
, a color CRT (Cathode Ray Tube) includes a panel
16
mounted on a front surface of the CRT, a fluorescent surface
15
coated with phosphor of R (Red), G (Green) and B (Blue) colors on the inner surface of the panel, a shadow mask
14
disposed on a rear portion of the fluorescent surface and serving to select color of the electron beams incident on the fluorescent surface, a funnel
13
connected to a rear portion of the panel and maintaining the inside of the funnel in a vacuum condition, an electron gun
11
mounted in the inside of a neck part of a tube type disposed at a rear portion of the funnel for emitting the electron beams, and a deflection yoke
20
surrounding the outside of the funnel
13
and mounted for deflecting the electron beams horizontally or vertically.
The deflection yoke
20
includes a horizontal deflection coil
21
, a vertical deflection coil
22
, a ferrite core
23
, a holder
24
and a compensating circuit board
25
. As shown in
FIG. 3
, a compensating circuit is divided into a compensating circuit using the vertical deflection coil and a vertical deflection current and another compensating circuit using a horizontal deflection coil and a horizontal deflection current. For the compensating circuit using the vertical deflection current, there are a tilt compensating circuit, an YBH (Y-axis Bow Horizontal) compensating circuit, an YCH (Y-axis Cross Horizontal) compensating circuit, a 4 poles CY (Convergence Yoke) coil, a CCV (Corner Cross Vertical) MCM (Magnetic Current Modulation), an inner MCM (Magnetic Current Modulation), and so on. For the compensating circuit using the horizontal deflection current, there are a balance coil, a cancel coil, a CCV MCM, an inner MCM, and so on. The tilt compensating circuit has a variable resistance R
16
, which is connected in series between resistances R
1
and R
2
, connected to vertical deflection coils L
1
and L
2
. The YBH compensating circuit includes a variable resistance R
7
connected in series to the vertical deflection coil, four rectifying diodes D
1
, D
2
, D
3
and D
4
connected in rows to the variable resistance, a compensating coil L
4
connected in rows to the rectifying diode D
2
and another compensating coil L
5
connected in rows to the diode D
1
.
The YCH compensating circuit is connected in rows to resistances R
10
and R
13
and adjusts a variable resistance R
12
by current flowing in a resistance R
11
. The 4 poles CY coils L
6
and L
7
are connected in rows to the diode D
4
and the resistance R
9
connected in series, to the diode D
3
and a resistance R
14
connected in series, and coils L
4
and L
5
connected in rows. The inner MCM L
8
is connected in rows to a resistance R
15
and connected to the 4 poles CY coils L
6
and L
7
.
A conventional deflection yoke makes horizontal deflection currents Ih (+) and Ih (−) of a several ampere [A], which has frequency of 15.75 KHz or more, flow into the horizontal deflection coil and deflects the electron beams inside the color CRT horizontally using magnetic field generated by the horizontal deflection currents. Moreover, the conventional deflection yoke makes vertical deflection currents Iv (+) and Iv (−) of about 1[A], which has frequency of 60 Hz, flow into the vertical deflection coil and deflects the electron beams vertically using magnetic field generated by the vertical deflection currents. A self convergence type deflection yoke adjusts winding distribution of the horizontal deflection coil and the vertical deflection coil and makes barrel or pin-cushion type magnetic fields by each part (i.e., an opening part, a center part and a neck part), so that the barrel or pin-cushion type magnetic fields are converged on the same point from different distances, i.e., on a screen being a arrival place from a starting place. Because only before-mentioned deflection coil cannot satisfy laster distortion and convergence characteristics due to flatness, scale-up and high resolution of the screen, the convergence characteristics are adjusted using the convergence compensating circuit. To compensate misconvergence, such as YBH, YCH, tilt, VCR and others, occurred due to the flatness of the screen, a convergence compensating circuit
25
including a full-wave rectifying circuit, a balance coil and a CY coil using the diodes is mounted on the neck part of the deflection yoke.
Furthermore, in case that the current is flowed in the deflection coil to make the magnetic field, a ferrite core of high permeability is used to minimize a loss in a feedback path of the magnetic field, thereby increasing the magnetic field efficiency and the magnetic force. The variable resistance R
16
adjusts an amount of current flowing in right and left vertical deflection coils to compensate the tilt. To compensate the inner MCM and the CCV (Corner Cross Vertical), auxiliary coils L
3
and L
8
for compensating the MCM are connected in series to the vertical deflection current for synchronizing the horizontal deflection current and the vertical deflection current. To compensate the YCH, the variable resistance R
12
adjusts the current flowing in the auxiliary compensating coils L
4
and L
5
, and YBH compensation amounts of 12 o'clock direction and 6 o'clock direction are adjusted. Moreover, to compensate the YBH, the variable resistance R
7
is adjusted to adjust the current flowing in the auxiliary compensating coils L
4
and L
5
. To compensate the VCR, the auxiliary compensating coils L
6
and L
7
are connected in series to the vertical deflection coil.
The balance coil L
13
adjusts the currents of the upper and lower horizontal deflection coil, so that the screen distortion due to the linear symmetry of the horizontal deflection coil is compensated. Auxiliary coils L
10
and L
12
for compensating the CCV is connected to the horizontal deflection coil connected in parallel to compensate the CCV and is connected in series to the horizontal deflection coils L
9
and L
10
connected in parallel to compensate the inner pin-cushion.
The compensating circuits attached on the conventional deflection yoke have a restricted use only for adjusting the convergence characteristics.
Moreover, conventional color CRTs do not have the deflection circuits of oneself, differently from display devices such as LCDs or PDPs, and therefore, it is necessary to adjust the characteristics of the deflection yoke according to consumers' development styles when being manufactured. Generally, in a supply and demand condition that a yearly consumption of the color CRTs by the consumers is maximally tens of thousands and a yearly production of the color CRTs by suppliers is at least one million, the present system that must change the manufacturing conditions of suppliers according to the demand of consumers is very irrational.
The present system will be described hereinafter in more detail. A color CRT provider provides tubes, on each of which a deflection yoke is mounted, to a consumer, i.e., a set manufacturer, and the set manufacturer applies them to a new model using a chassis deflection circuit, which is old model. At this time, for impedance matching between the provided deflection yoke and the deflection circuit of the chassis, the set manufacturer requires an adjustment in characteristic of the deflection yoke to the color CRT provider. To adjust the characteristic of the deflection yoke, especially, inductance (L), the number of turns of the deflection coil must be adju
Kim Ji-Hyun
Lee Young-Wook
Fleshner & Kim LLP
LG Electronics Inc.
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