Electric lamp and discharge devices: systems – Cathode ray tube circuits – Cathode-ray deflections circuits
Reexamination Certificate
2002-01-29
2004-03-02
Vu, David (Department: 2821)
Electric lamp and discharge devices: systems
Cathode ray tube circuits
Cathode-ray deflections circuits
C396S408000
Reexamination Certificate
active
06700336
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a deflection power supplying apparatus for use in a display and a control method thereof, and more particularly to a deflection power supplying apparatus for use in a display capable of lowering a switching loss and a control method thereof. The present application is based on Korean Application No. 2001-9512, filed Feb. 24, 2001.
2. Description of the Related Art
FIG. 1
shows a circuit diagram showing a conventional deflection power supplying apparatus.
Referring to
FIG. 1
, the deflection power supplying apparatus includes a rectifying portion
11
, a pulse width modulation controlling portion (PWM controlling portion;
13
), a first transformer
15
, a LC filtering portion
17
, a second transformer
19
, and a horizontal driver
23
.
A first switch
12
is installed to control a power supply to a first coil of the first transformer
15
with the PWM controlling portion
13
. Connected in parallel with the first switch
12
, a capacitor
14
is aimed to generate resonance in association with the first coil of the first transformer
15
. More specifically, the capacitor restricts an increase of voltage at both ends of the first switch
12
at the time of turning off of the first switch
12
, and lowers switching loss at the time the first switch
12
is turned on.
A first coil of the second transformer
19
is connected to a second coil of the first transformer
15
to form an electric current loop, while the second coil is connected to a rectifying element to output a high voltage generated by a winding ratio.
Installed on the electric current loop connected between the first coil of the second transformer
19
and the second coil of the first transformer
15
, the second switch
25
is switched on/off by a horizontal driver
23
.
A deflecting coil
21
, called a deflection yoke, is connected in parallel with the second switch
25
to form electric loop.
The element designated by a reference symbol S.R is an inductor for suppressing a parasitic component.
The deflection power supplying apparatus described above is generally called a pseudo-resonant flyback converter. In the deflection power supplying apparatus, electric current is applied to the first transformer
15
in a discontinuous current mode, and the maximum electric current at the first switch
12
is increased to more than twice the value of a normal load electric current. Further, since the maximum value of the switching voltage at the first switch
12
is the result of adding output voltage of input voltage at the first coil, switching stress is increased, deteriorating power transfer efficiency.
Additionally, due to the considerable number of components, the structure becomes complicated. Also, since the switches are driven by the variable-frequency method, it is difficult to design the LC filter
17
in order to improve filtering capability.
FIG. 2
is a circuit diagram showing a conventional deflection power supplying apparatus according to another method.
Referring to
FIG. 2
, the deflection power supplying apparatus includes a rectifying portion
31
, a pulse width modulation controlling portion (PWM controlling portion;
33
), a LC filter
37
, a high voltage transformer
39
, and a horizontal driver
43
.
A first switch
32
is installed to control a power supply from the rectifying portion
31
to a first coil of the high voltage transformer
39
with the PWM controlling portion
33
.
The LC filter
37
is connected between the first switch
32
and the first coil of the high voltage transformer
39
, to suppress noise input through the first switch
32
and noise directed from the high voltage transformer
39
to the rectifying portion
31
.
The second coil of the high voltage transformer
39
is connected to the rectifying element, to thereby output high voltage generated by the winding ratio.
The second switch
45
is installed on the electric current path connected from the first coil of the high voltage transformer
39
to the rectifying portion
31
, and switched on/off by the horizontal driver
43
.
The deflecting coil
41
is connected in parallel with the second switch
45
to form an electric current loop.
The deflection power supplying apparatus as described above is generally called a buck converter. The operation of the buck converter will be described below.
The PWM controlling portion
33
controls duty, a ratio of the interval, where the first switch
32
is driven on, with respect to the driving period, according to required electricity supply, and drives on/off the first switch
32
.
The maximum electric current input through the first switch
32
is determined as a normal load electric current driven in a continuous current mode, and the maximum voltage at both ends of the first switch
32
are determined as input voltage.
The high voltage transformer
39
induces energy stored at the first coil through the LC filter
37
for smoothing and noise removal to the second coil by the flyback method, generating high voltage. The energy, induced at the second coil of the high voltage transformer
39
, is output as high voltage for thermal electron emission.
The horizontal driver
43
regularly drives on/off the second switch
45
in accordance with the frequency of the horizontal sync signal. While the second switch
45
is turned on, energy is stored at the first coil of the high voltage transformer
39
, and the deflecting coil
41
generates the electric current required for horizontal scanning of a screen. While the second switch
45
is turned off, the energy stored at the first coil of the high voltage transformer
39
is transmitted to the second coil, and the deflecting coil
41
generates retrace electric current that is required to emit a beam to a horizontal scanning upper end.
Since the deflection power supplying apparatus as described above, however, can not share the functions of some elements, the structure becomes complicated. Further, when the energy stored at the first coil of the high voltage transformer
39
flows toward the LC filter
37
, i.e., when the energy flows in the reverse direction during the time the first and the second switches
32
and
45
are switched off altogether, energy is almost charged through the capacitor
37
a
. As a result, switching loss occurs when the first switch
32
is turned on, and it is hard to control the generation of the switching noise.
SUMMARY OF THE INVENTION
The present invention has been made to overcome the above-mentioned problems of the related art, and accordingly, it is an object of the present invention to provide a deflection power supplying apparatus for use in a display and a control method thereof capable of simplifying a structure for supplying deflection electric current and also lowering switching loss.
The above object is accomplished by an apparatus for supplying a deflection power for use in a display in accordance with the present invention, including a rectifying portion for rectifying an alternating electric current into a direct electric current, a high voltage outputting portion having a first coil connected on an output path of a voltage rectified by the rectifying portion and a second coil coupled with the first coil, the high voltage outputting portion for outputting a voltage induced at the second coil, a first switching portion installed between the rectifying portion and the first coil, for controlling a power supply, a second switching portion installed on a path formed from the first switching portion, the first coil, and the rectifying portion, for controlling the power supply, and a deflection electric current generating portion forming a loop of electric current in parallel in association with both ends of the second switching portion, the deflection electric current generating portion connected in series with a deflection coil and a capacitor.
The high voltage outputting portion includes a diode, an anode of which being connected to one end of the second coil, and a capacitor connected between a cathode of t
Kim Young-Soo
Roh Chung-Wook
Yang Jun-Hyun
Sughrue & Mion, PLLC
Vu David
LandOfFree
Apparatus for supplying deflection power for use in a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for supplying deflection power for use in a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for supplying deflection power for use in a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3191604