JP4126630B2 - Piezoelectric transformer inverter and piezoelectric transformer - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an inverter using a piezoelectric transformer, and more particularly, to an output extraction structure of a piezoelectric transformer.
[0002]
[Prior art]
In recent years, studies on power supply circuits such as an inverter for a backlight of a liquid crystal display using a piezoelectric transformer and a DC / DC converter have been actively conducted. This is because the power supply circuit can be dramatically reduced in size and thickness by employing a piezoelectric transformer.
[0003]
In this backlight inverter, a high voltage of about 1500 V is generated at the start of lighting in order to light a cold cathode tube or the like. In such a high voltage circuit, it is necessary to take safety measures such as a spatial distance, a creepage distance, and an insulation distance between the high voltage side circuit unit and the low voltage side circuit unit.
[0004]
FIG. 6 shows a conventional example in which this safety measure is taken. This shows a part of the printed circuit board of the piezoelectric transformer inverter. 6A shows the front surface, and FIG. 6B shows the back surface. A piezoelectric transformer is mounted on the broken line 20 in FIG. The lands 24 and 25 are output lands for the piezoelectric transformer, and the lands 22 and 23 are input lands for the piezoelectric transformer. FIG. 7 shows this conventional piezoelectric transformer. The piezoelectric transformer 1 has a laminated structure in which input electrodes 2 are alternately formed at the center, and output electrodes 4 are formed at both ends. The lead wire 3 is soldered to the input electrode 2 and the output electrode 4. The piezoelectric transformer 1 is housed in a protective case 5 and each lead wire 3 is wound around a connection terminal 8. In FIG. 7, 6 is a terminal block, 7 is a mounting terminal, and 11 is a lead-out hole.
[0005]
An output connector is attached to a portion indicated by a broken line 30 on the printed board 21. The output of the piezoelectric transformer 20 is connected to output lands 24 and 25, the lands 24 and 25 are connected by a connection conductor 27, and further connected to a high-voltage terminal of the output connector 30 by a connection conductor 28. The output connector 30 is connected to the high-voltage terminal land 31. The low voltage terminal land 32 of the output connector 30 is connected through a through hole from the back surface.
As a safety measure for the high-voltage side circuit and the low-voltage side circuit, a creeping distance is taken by using a double-sided printed board and providing a slit 26.
[0006]
[Problems to be solved by the invention]
One of the main applications of this piezoelectric transformer inverter is a notebook PC, but there is a strong trend toward large screens as well as miniaturization and thinning. This inverter can be downsized, especially narrow and thin. It is requested. For this reason, a sufficient space for ensuring safety between the high-voltage side circuit and the low-voltage side circuit cannot be obtained.
[0007]
In view of the above, an object of the present invention is to provide a piezoelectric transformer inverter having a novel structure that can reliably insulate a high-voltage circuit from a low-voltage circuit.
[0008]
[Means for Solving the Problems]
A first invention is a piezoelectric transformer in which a high voltage output terminal is formed and a piezoelectric ceramic transformer element is housed in a recess of a protective case having an output connector portion, the piezoelectric ceramic transformer element being formed in a rectangular shape, In the first aspect, two input terminal electrodes are disposed at the center, and one output terminal electrode is disposed at each end, and the protective case includes an input electrode terminal connected to the input terminal electrode, and the output terminal electrode. A projecting portion provided with a terminal for output electrode to be connected, and a second side surface facing the first side surface of the piezoelectric ceramic transformer element provided in the protective case portion by the spring property of the terminal for input electrode and the terminal for output electrode The high voltage output terminal is different from the piezoelectric ceramic transformer element in a protective case. A piezoelectric transformer, characterized by conducting two paths branching on the side and the output electrode terminals.
[0009]
In the present invention, it is preferable that the input electrode terminal is led out to the mounting surface of the protective case on the substrate.
[0010]
In the present invention, the protective case includes an inner case and an outer case, and the inner case includes an input electrode terminal, an output electrode terminal, a piezoelectric ceramic transformer element, and the output electrode terminal. A connection terminal that conducts, the outer case includes an output connector portion and a high-voltage terminal that serves as a high-voltage output terminal, the inner case is inserted into a housing space of the outer case, and the connection terminal and the high-voltage terminal It is preferable to connect the terminal.
[0011]
A second invention is a piezoelectric transformer inverter in which the piezoelectric transformer according to the first invention is mounted on a mounting board on which a conductive portion to which a high voltage output from a piezoelectric ceramic transformer element is connected is not formed .
[0012]
The present invention is also a piezoelectric transformer characterized in that the piezoelectric ceramic transformer element is a central drive type piezoelectric ceramic transformer element having an input electrode facing the center and output electrodes at both ends.
[0013]
The present invention is also the piezoelectric transformer characterized in that output electrodes formed at both ends of the piezoelectric ceramic transformer element are electrically connected by a conductive portion built in the protective case.
[0014]
The present invention is also a piezoelectric transformer inverter in which a piezoelectric transformer is mounted on a substrate, wherein an output connector of the piezoelectric transformer inverter and the piezoelectric transformer are integrally formed, and an output electrode of the piezoelectric transformer and the output A piezoelectric transformer inverter characterized in that a high voltage side terminal of a connector is connected by a conductive part provided in the protective case, and a conductive part to which the high voltage output of the piezoelectric ceramic is connected is not formed on the substrate. is there.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is a piezoelectric transformer inverter in which a piezoelectric transformer is mounted on a substrate, and an output connector of the piezoelectric transformer inverter and a piezoelectric transformer are integrally formed. This eliminates the need to form a high-voltage circuit on the substrate, ensuring safety and facilitating miniaturization.
[0016]
Conventionally, a piezoelectric transformer and an output connector are separately mounted on a substrate, and the output of the piezoelectric transformer is connected to the output connector by a conductive portion on the substrate. For this reason, it was necessary to take insulation measures on the substrate. In the present invention, by integrating the piezoelectric transformer and the output connector, it is possible to eliminate the necessity of providing a conductive portion for high-voltage output on the substrate. This eliminates the need to take insulation measures on the board, saves space, eliminates space waste that could not be mounted in the vicinity of high-voltage parts in the past, enables high-density mounting, and enables downsizing. is there.
[0017]
A partial cross-sectional view of one embodiment according to the present invention is shown in FIG. This embodiment includes a central drive type piezoelectric ceramic transformer element 41 and a protective case 42.
[0018]
A perspective view of the central drive type piezoelectric ceramic transformer element 41 is shown in FIG. The piezoelectric ceramic transformer element 41 is formed by stacking piezoelectric green sheets. The piezoelectric green sheet has an input electrode 43 at the center and output electrodes 45 at both ends. The input electrodes 43 are alternately connected to the input terminal electrodes 44 on the side surface. The output electrodes 45 at both ends are also connected to the output terminal electrodes 46 on the side surfaces.
[0019]
The protective case 42 is provided with output electrode terminals 47 and 48 connected to the output terminal electrode 46 of the piezoelectric transformer ceramic element 41 and input electrode terminals 49 and 50 connected to the input terminal electrode 44. The output electrode terminals 47 and 48 are electrically connected in the protective case 42, and are electrically connected to the high voltage output terminal 53 of the output connector portion 55. Although not shown, the input electrode terminals 49 and 50 are led out to the mounting surface of the protective case 42 and are configured to be connectable to lands on the substrate. Further, the low voltage side terminal 54 of the output connector portion 55 is drawn out to the end face side opposite to the output connector portion 55 of the protective case 42, and is configured to be connectable to a land on the board. In addition, 51 of the protective case 42 is a housing recess for the piezoelectric ceramic transformer element 41, and 52 is a protrusion for supporting the piezoelectric ceramic transformer element 41. Further, the output electrode terminals 47 and 48 and the input electrode terminals 49 and 50 are structured to support the piezoelectric ceramic transformer element 41 by springiness.
[0020]
According to the present embodiment, the output of the piezoelectric transformer is directly connected to the high-voltage terminal of the output connector, and the connecting conductor portion is formed in the protective case to ensure insulation. Thereby, a highly safe piezoelectric transformer inverter can be configured. Of course, the mounting board of this embodiment does not require a high-voltage land and a high-voltage line, and only constitutes the input line of the piezoelectric transformer and the low-voltage line of the output connector, and it is not necessary to take measures against high voltage. . Therefore, miniaturization and high-density mounting are possible.
[0021]
Another embodiment according to the present invention is shown in FIGS. FIG. 3 shows an inner case 61 that uses the piezoelectric ceramic transformer element 41 shown in FIG. 2 and holds it. In this inner case 61, the piezoelectric ceramic transformer element 41 is accommodated in the piezoelectric ceramic transformer element 41 accommodating portion 62, the output electrode terminals 63 and 64 are connected to the output terminal electrode 46 of the piezoelectric transformer ceramic element 41, and the input terminal electrode 44, input electrode terminals 65 and 66 are connected. The output electrode terminals 63 and 64 and the input electrode terminals 65 and 66 have a structure that supports the piezoelectric ceramic transformer element 41 by a spring property. In the figure, reference numeral 69 denotes a protrusion that supports the piezoelectric ceramic transformer element 41. The output electrode terminals 63 and 64 are electrically connected in the inner case 61 and are electrically connected to a terminal 67 that is electrically connected to the high voltage output terminal of the output connector portion. In addition, a conductive portion 70 that is connected to a terminal 68 that is connected to a low-voltage output terminal of the output connector portion extends to the other end.
[0022]
FIG. 4 shows an outer case 71 of the protective case, which has a space 72 for accommodating the inner case 61 of FIG. 3 and includes an output connector portion 73. The output connector 73 includes a high voltage terminal 74 and a low voltage terminal 75.
[0023]
FIG. 5 is a partial cross-sectional view showing a state where the inner case 61 of FIG. 3 is mounted on the outer case 71 of FIG. In this embodiment, the inner case 61 is inserted into the storage space 72 of the outer case 71, the high voltage terminal 74 and the terminal 67 connected to the output electrode terminals 63 and 64 are connected, and the low voltage terminal 75 and the terminal 68 are connected. Connected and configured. In this state, it is mounted on the mounting board. In this embodiment, although not shown, the input electrode terminals 65 and 66 are led out to the mounting surface and connected to the input lands on the mounting board. The terminal 68 connected to the low voltage terminal 75 is also led out to the mounting surface and connected to the low voltage land on the mounting board.
[0024]
In the embodiment of the present invention, since the piezoelectric transformer and the output connector are integrated, the output of the piezoelectric transformer is connected as it is to the high voltage terminal of the output connector, and the connecting conductor portion is formed in the protective case and insulated. Is secured. Thereby, a highly safe piezoelectric inverter can be configured. Of course, the mounting board of this embodiment does not require a high-voltage land and a high-voltage line, and only constitutes the input line of the piezoelectric transformer and the low-voltage line of the output connector, and it is not necessary to take measures against high voltage. . Therefore, miniaturization and high-density mounting are possible.
[0025]
Further, according to the present invention, a conductor connecting the two output electrodes of the piezoelectric transformer is also provided in the protective case, so that the connection between the output electrodes on the substrate can be eliminated, and the countermeasure for high voltage on the substrate is eliminated. ing.
[0026]
In the above embodiment, the piezoelectric ceramic transformer element having a central drive type laminated structure has been described. However, the piezoelectric ceramic transformer element having other configurations can have the same configuration, and the same effect can be obtained.
[0027]
【The invention's effect】
According to the present invention, in a piezoelectric transformer inverter in which a piezoelectric transformer is mounted on a substrate, a conductive portion for high-voltage output can be eliminated from the substrate by integrating the output connector of the piezoelectric transformer inverter and the piezoelectric transformer. Insulation measures on the substrate can be eliminated. As a result, the reliability of the high-voltage circuit can be improved, and high-density mounting and miniaturization can be achieved.
[Brief description of the drawings]
FIG. 1 is a partial sectional view of an embodiment according to the present invention.
FIG. 2 is a perspective view of a piezoelectric ceramic transformer element according to an embodiment of the present invention.
FIG. 3 is a plan view of an inner case according to another embodiment of the present invention.
FIG. 4 is a plan view of an outer case of another embodiment according to the present invention.
FIG. 5 is a partial cross-sectional view of another embodiment according to the present invention.
FIG. 6 is a plan view and a back view of a conventional mounting substrate.
FIG. 7 is a perspective view of a conventional central drive type piezoelectric transformer element.
[Explanation of symbols]
41 Central drive type piezoelectric transformer element 42 Protective case 43 Input electrode 45 Output electrode 44 Input terminal electrode 46 Output terminal electrodes 47, 48, 63, 64 Output electrode terminals 49, 50, 65, 66 Input electrode terminals 53, 74 High voltage Output terminals 54, 75 Low voltage output terminals 55, 73 Output connector 61 Inner case (protective case)
71 Outer case (protective case)

Claims (4)

A piezoelectric transformer in which a high-voltage output terminal is formed and a piezoelectric ceramic transformer element is housed in a recess of a protective case provided with an output connector part,
The piezoelectric ceramic transformer element is formed in a rectangular shape, and on its first side surface, two input terminal electrodes are arranged at the center, and one output terminal electrode is arranged at both ends,
The protective case includes an input electrode terminal connected to the input terminal electrode and an output electrode terminal connected to the output terminal electrode. Depending on the spring property of the input electrode terminal and the output electrode terminal, a piezoelectric ceramic transformer is provided. The second side surface facing the first side surface of the element is in contact with the protrusion provided in the protective case portion to support the piezoelectric ceramic transformer element,
The piezoelectric transformer, wherein the high-voltage output terminal is electrically connected to the output electrode terminal through two paths branched to different side surfaces of the piezoelectric ceramic transformer element in a protective case. The piezoelectric transformer according to claim 1, wherein the input electrode terminal is led out to a mounting surface of the protective case on the substrate. The protective case includes an inner case and an outer case,
The inner case includes an input electrode terminal, an output electrode terminal, a piezoelectric ceramic transformer element, and a connection terminal electrically connected to the output electrode terminal.
The outer case includes an output connector portion and a high voltage terminal serving as a high voltage output terminal, the inner case is inserted into a housing space of the outer case, and the connection terminal and the high voltage terminal are connected. The piezoelectric transformer according to claim 1 or 2. The piezoelectric transformer according to claim 1 is mounted on a mounting board, and the mounting board is not formed with a conductive portion to which a high voltage output from the piezoelectric ceramic transformer element is connected. Piezoelectric transformer inverter.

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