Electric lamp and discharge devices: systems – Periodic switch in the supply circuit – Silicon controlled rectifier ignition
Reexamination Certificate
2000-03-17
2001-09-25
Philogene, Haissa (Department: 2821)
Electric lamp and discharge devices: systems
Periodic switch in the supply circuit
Silicon controlled rectifier ignition
C315S276000, C315S2090SC, C310S311000, C310S348000, C310S344000
Reexamination Certificate
active
06294878
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a piezoelectric transformer used for the inverter for lighting the backlight of a liquid crystal display, the inverter for lighting a fluorescent lamp and the high-voltage power circuit of a copier or the like, and the piezoelectric inverter and the liquid crystal display using the same.
2. Description of the Related Art
As a well known piezoelectric transformer, there is a Rosen type piezoelectric transformer comprising a driving section wherein a pair of input electrodes are formed on a rectangular planar piezoelectric plate and which is polarized in the thickness direction, and a power generation section wherein an output electrode is formed on the end face in the longitudinal direction and which is polarized in the longitudinal direction. This type of piezoelectric transformer is constituted so as to mechanically vibrate the piezoelectric plate by applying an input voltage to the input electrodes via the input side wiring, and to take out the output voltage of AC high voltage generated at the output electrode via the output side wiring. As a lead for each the above-mentioned wiring, a lead that least inhibits vibration and that is not broken by vibration is desired. There is proposed, therefore, a piezoelectric transformer using, as leads for wiring, gold thread wires which have a flexibility and a good vibration-following property (Japanese Unexamined Patent Publications No. 8-32139 and No. 8-64884).
Conventional gold thread wires used as leads for wiring of a piezoelectric transformer are classified into three types as follows: a type having a structure wherein a copper foil (metallic foil)
7
b
in the shape of band is singly wound spirally around a core
7
a
consisting of numerous fine wires bundled, as shown in
FIG. 6A and 6B
; a type having a structure wherein two copper foils
7
b
are doubly wound around the core
7
a
in the same direction to increase the mechanical strength (bending strength), as shown in
FIG. 7A
; and a type having a structure wherein two copper foils
7
b
are doubly wound around the core
7
a
in the directions such that the two copper foils intersect each other, as shown in FIG.
7
B. These gold thread wires are soldered at the input electrodes or the output electrode for connection.
However, in the conventional piezoelectric transformer using the above-described gold thread wires, there has been problems that, when a gold thread wire contacts or approaches the piezoelectric plate or a mounting board in the vicinity of the gold thread wire, it vibrates concurrently with the vibration of the piezoelectric transformer during operation, thereby causing soundings, and wearing copper foils of the gold thread wire, with the result that it becomes thin, and incurs a bad electrical conduction, or even a breaking under certain circumstances.
Further, there has been another problem that, when using a gold thread wire with doubly-wound copper foils, the friction between copper foils causes the copper foils to wear, thereby incurring the thinning or breaking of the wire.
Moreover, because the copper foil of a conventional gold thread wire directly contacts air, the copper foil is oxidized with time, and thereby its solderability (wettability toward solder) deteriorates, so that adequate fillets for soldering may be not formed, providing a bad soldering.
Also, there have been a problem that, when soldering a conventional gold thread wire, solder is easily wicked to the outer peripheral surface and the inside of the gold thread wire, thereby the solder wicked impairing the flexibility of the gold thread wire, and inhibiting (suppressing) the vibration of the piezoelectric transformer, which results in the deterioration of the performance of the piezoelectric transformer.
In recent years, there is an growing need for the size reduction of equipment using a piezoelectric transformer, and accordingly, the size reduction of the piezoelectric transformer itself is also strongly demanded. Now that the shortening of the gold thread wire for wiring having thus become a necessity for the piezoelectric transformer, the above-described problems are increasingly manifesting themselves.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a piezoelectric transformer, a piezoelectric inverter, and a liquid crystal display with a high reliability, capable of preventing the occurrence of the soundings caused by the contact between gold thread wires and preventing the breaking of the gold thread wires and the deterioration of the performance of the piezoelectric transformer.
In order to achieve the above-described object, the piezoelectric transformer in accordance with the present invention is characterized by a piezoelectric transformer which has a piezoelectric transformer element disposed on a mounting board and which uses gold thread wires for connecting the electrode of the piezoelectric transformer element and the electrode of the mounting board, wherein the metallic foil of the gold thread wires are coated with a coating material.
Also, the piezoelectric transformer in accordance with the present invention is characterized by a piezoelectric transformer which has a piezoelectric transformer element disposed on a mounting board and which uses gold thread wires for connecting the electrode of the piezoelectric transformer element and the electrode of the mounting board, wherein the gold thread wires are coated with, and penetrated into by a coating material.
As a coating material as mentioned above, a resin adhesive such as a flexible silicone-base adhesive, or a lubricant such as silicone oil or grease may be used.
The piezoelectric inverter in accordance with the present invention is characterized by comprising the abovedescribed piezoelectric transformer.
The liquid crystal display in accordance with the present invention is characterized by comprising the abovedescribed piezoelectric transformer or piezoelectric inverter.
In accordance with the piezoelectric transformer having the above-described constitution, even if the gold thread wire vibrates at the state of contacting members in the vicinity, it slips off the members contacted by virtue of the coating material, or its conditions of contact with the members is mitigated by the coating material. This permits the prevention of the occurrence of soundings and the wear of metallic foil. Further, in the case of the gold thread wire with doubly-wound metallic foils, or triply-wound metallic foils, it is possible to prevent the metallic foil from the wear due to the friction between the metallic foils by inserting the coating material between the metallic foils. Thereby the gold thread wire can be prevented from thinning or breaking.
Further, the metallic foil of the gold thread wire is separated from air by the coating material, and hence it can be prevented from oxidation. This allows the avoidance of a bad soldering such as a cold joint due to the oxidation of gold thread wire.
In addition, by making the coating material penetrate to the inside of the gold thread wire (core portion), it is possible to suppress the wicking of solder to the inside of the gold thread wire during soldering. This allows the flexibility of the gold thread wire to be maintained, and thereby allows the performance of the gold thread wire to be prevented from deterioration.
Since the piezoelectric inverter in accordance with the present invention is constituted so as to comprise a piezoelectric transformer possessing the above-described features, it has an excellent performance and a high reliability.
Also, since the liquid crystal display in accordance with the present invention is constituted so as to comprise a piezoelectric transformer or piezoelectric inverter possessing the above-described features, it has an excellent performance and a high reliability.
REFERENCES:
patent: 5753381 (1998-05-01), Feldman et al.
patent: 5998909 (1999-12-01), Kumasaka et al.
patent: 5998938 (1999-12-01), Comberg et al.
pate
Murata Koji
Nishikawa Etsuo
Murata Manufacturing Co. Ltd.
Ostrolenk Faber Gerb & Soffen, LLP
Philogene Haissa
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