Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
2001-06-28
2003-07-01
Zarroli, Michael C. (Department: 2839)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C310S366000
Reexamination Certificate
active
06586863
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a Rosen type piezoelectric transformer constituting a stabilizer for cold cathode fluorescent lamps used for a back light of a liquid crystal display (LCD) device. More particularly, the present invention relates to a Rosen type piezoelectric transformer with multiple output electrodes for lighting a plurality of cold cathode fluorescent lamps at the same time by forming multiple output electrodes as one body, and a stabilizer for multiple light sources using such Rosen type piezoelectric transformer.
2. Description of the Prior Art
As is well known to those skilled in the art, a fluorescent lamp needs high voltage at initial lighting in order to emit the required thermal electrons for an electric discharge. After electric discharge, the voltage impressed on the fluorescent lamp has negative resistance characteristics reduced when the lamp current increases.
Especially, a cold cathode fluorescent lamp that is used for a backlight of a liquid crystal display (LCD) device is a light source using cold emission (electron emission caused by forcing a strong electric field to a cathode surface). In order to light the backlight comprised of the cold cathode fluorescent lamp, about 500 V is needed. Generally, a step-up transformer is used to convert a commercial AC power source into the driving voltage.
The stabilizer is a lamp lighting device that applies the driving voltage for lighting the fluorescent lamp with the above mentioned properties, and comprises, as shown in
FIG. 7
, a rectifying section
621
which rectifies an AC commercial source
61
to DC voltage in some level, a power factor compensation section
622
for compensating the power factor caused by the fluctuation of the AC commercial voltage source in respect of the output voltage of the rectifying section
621
, an AC voltage generating section
623
for converting the DC voltage inputted through the power factor compensation section
622
into a proposed AC voltage of high frequency, and a resonating section
624
for resonating with the output voltage of the AC voltage generating section
623
and supplying the AC voltage to the fluorescent lamp
63
.
As above-mentioned, the AC voltage generating section
623
is called an inverter.
The resonating section
624
is conventionally constructed to generate the resonance by the inductance of a winding type transformer and the capacitance of a resonance capacitor in connection with the winding type transformer. But the winding type transformer has some problems in that it produces a high rate of poor quality and the credibility of the stabilizer is reduced because the deviation of the quality of core is excessive. For this reason, the winding type transformer has recently been replaced with a piezoelectric transformer such that the resonance is generated by the inductance of the inductor with the capacitance of the piezoelectric transformer.
But the above statement is the case of connecting one fluorescent lamp to one stabilizer. On the other hand, in a case of lighting more than two fluorescent amps by connecting the fluorescent lamps into one stabilizer, if one of numerous fluorescent lamps is lighted, other fluorescent lamps connected to the wound-type transformer in parallel are not lighted because a lower voltage is supplied to the other fluorescent lamps by lighting the one fluorescent lamp.
Accordingly, in the case of connecting two or more fluorescent lamps to one stabilizer, as shown in
FIGS. 8 and 9
, the ballast capacitor is directly connected between fluorescent lamps
72
,
82
and transformers
712
,
812
such that the voltage required for initial lighting is impressed on the fluorescent lamps
72
,
82
even if a certain fluorescent lamp is lighted ahead of the fluorescent lamps
72
,
82
.
Hence, the conventional stabilizer used for a plurality of light sources is constructed as shown in
FIGS. 8 and 9
.
As is shown in
FIG. 8
, the stabilizer
71
, for a plurality of fluorescent lamps having a wound-type transformer, comprises a circuit section
711
, which includes the rectifying section
621
, the power compensating section
622
, the AC voltage generating section
623
, and the resonance capacitor of the resonating section
624
, the wound-type transformer
712
, the input electrode of which is connected to the resonance capacitor of the circuit section
711
, and a plurality of ballast capacitors
713
that are connected to an output electrode of the wound-type transformer
712
in parallel. The number of ballast capacitors is the same as the number of lamps. Furthermore, a plurality of fluorescent lamps
72
is connected to the other terminal of the plurality of ballast capacitors
713
of the stabilizer
71
, respectively.
As is shown in
FIG. 9
, the stabilizer
81
for a plurality of fluorescent lamps having a piezoelectric transformer comprises a circuit section
811
, which includes the rectifying section
621
, the power compensating section
622
, the AC voltage generating section
623
, and the resonance capacitor of the resonating section
624
, the piezoelectric transformer
812
, the input electrode of which is connected to a resonance capacitor of the circuit section
811
, and a plurality of ballast capacitors
813
that are connected to an output electrode of the piezoelectric transformer
812
in parallel. Furthermore, the plurality of fluorescent lamps
82
is connected to the other terminal of the plurality of ballast capacitors
813
of the stabilizer
81
, respectively.
In the stabilizer above, because AC voltage supplied by the wound-type transformer
712
or the piezoelectric transformer
812
is divided equally among the plurality of fluorescent lamps via the ballast capacitor
713
,
813
, the plurality of fluorescent lamps can be lighted at the same time. The ballast capacitor
713
,
813
has a high withstand voltage characteristic, and its size is also big.
Accordingly, as is shown in
FIG. 8
or
FIG. 9
, because the stabilizer needs the ballast capacitors in proportion to the number of the connected fluorescent lamps, the volume and the number of components increase, and the cost increases also.
Thus, in the case of constituting a stabilizer as mentioned above, there have been some problems in that the number of components and the volume increases and the production costs rise because the number of ballast capacitors required is proportionate to the number of connected fluorescent lamps.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a Rosen type piezoelectric transformer having a plurality of output electrodes with uniform output properties which make the fluorescent lamp light stably, the operation be simple, and the cost be reduced.
The present invention provides a Rosen type piezoelectric transformer with multiple output electrodes, being used for a stabilizer to light a plurality of cold cathode fluorescent lamps, comprising: a piezoelectric plate; an input electrode formed at an upper surface of the plate; a plurality of output electrodes having an identical band shape, arranged in equal distance in the longitudinal direction of the plate at an outer side of the input electrode, and connected electrically to one ends of the plurality of the cold cathode fluorescent lamps, respectively; and a common electrode formed at a bottom surface of the plate, confronting to the input electrode, commonly connected to ground of the stabilizer and the other ends of the plurality of the cold cathode fluorescent lamps.
REFERENCES:
patent: 5751092 (1998-05-01), Abe
patent: 5892318 (1999-04-01), Dai et al.
patent: 5929554 (1999-07-01), Kanayama et al.
patent: 5962954 (1999-10-01), Leers et al.
patent: 6188163 (2001-02-01), Danov
patent: 6278226 (2001-08-01), Danov et al.
patent: 6362560 (2002-03-01), Yang et al.
Kim Jong-Sun
Youm Jang-Hyoun
Renner , Otto, Boisselle & Sklar, LLP
Samsung Electro-Mechanics Co. Ltd.
Zarroli Michael C.
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