JP4999315B2 - Piezoelectric transformer - Google Patents

Description

  The present invention relates to a piezoelectric transformer using piezoelectric ceramics as an element for generating a high voltage and as an element for converting a voltage.

  Piezoelectric transformers using piezoelectric ceramics are widely used, for example, as a light source for a backlight that illuminates a liquid crystal used in a personal computer or the like from the back side, a DC-DC converter of a power supply device, a high voltage power source such as an air cleaner, and the like. Yes. In this type of piezoelectric transformer, primary and secondary electrodes are provided on piezoelectric ceramics such as PZT, and the crystal axes are aligned and polarized by applying a high electric field.

  FIG. 5 shows a side view of this type of piezoelectric transformer. The piezoelectric transformer 6 ′ is provided with primary electrodes 2 ′ and 3 ′ on the upper and lower surfaces of one half of the piezoelectric ceramic 1 ′, respectively, and the secondary electrodes 4 ′ and the upper and lower surfaces on the outer end side of the other half. 5 'is provided and configured.

  When a voltage having a natural resonance frequency determined by the length direction of the primary side is applied between the primary side electrodes 2 ′ and 3 ′, a voltage corresponding to the vibration can be taken out from the secondary side by the inverse piezoelectric effect.

  The voltage application to the primary side is performed via lead wires 10 'and 11' connected to the approximate center of the primary side electrodes 2 'and 3' using solder 9 '.

The secondary output is taken out via the other end of the lead wire 8 'by connecting one end of the lead wire 8' to the secondary electrode 5 'using solder 9'.
Japanese Patent Application No. 2002-276808

  In this case, if the amount of the solder 9 'is large, the weight of the solder 9' is added to that amount, and when the end of the piezoelectric ceramic 1 'vibrates, it becomes a vibration load, resulting in reduced efficiency and abnormal heat generation. Since there is a fear, the amount of solder 9 'should be as small as possible.

  Further, conventionally, since a device for positioning that connects one end of the lead wire 8 ′ to a predetermined position of the secondary electrode 5 ′ has not been taken, for example, as shown in FIGS. 6 (a) and 6 (b), solder 9 As shown in FIGS. 7A and 7B, the position of 'may be misaligned, and the amount of solder 9' to be stacked may also be gusseted, which may cause variations in characteristics for each product.

  The piezoelectric ceramics 1 'applies a high voltage, and as shown by an arrow A in FIG. 8, for example, the power generation unit and the output unit are polarized with the crystal axes aligned.

  In this case, the direction of the crystal axis at the end of the output portion is as shown by an arrow A ′ in FIG. 9, and a polarization interface B is generated in the secondary electrode 4 ′, 5 ′ portion. Structurally weak.

  Therefore, the amount of the solder 9 'is large, and there is a possibility that the polarization interface B is cracked due to the defective vibration caused by the vibration load, thereby being damaged.

  This invention has been proposed in view of the above, and its purpose is to connect the soldering position of the lead wire to the secondary electrode, position the soldering position, and reduce the solder diameter. Provided is a piezoelectric transformer that can be connected with a small amount of solder and that reduces vibration load due to the weight of the solder.

The invention according to claim 1 is a piezoelectric transformer in which the piezoelectric ceramic includes a primary electrode for voltage input and a secondary electrode for voltage output. The secondary electrode has a long side along the width direction of the piezoelectric ceramic. And a short side, and a slit is formed inside one of the secondary electrodes to narrow the soldering area along the long side, and the outside of the slit is soldered. It is characterized by the attachment part .

  According to the first aspect of the present invention, the slit on which solder is not placed is formed on at least one of the primary side electrode and the secondary side electrode, the soldering position is narrowed by the slit, and the slit is positioned by the slit. Since the solder does not get on the slit portion, the amount of solder of each electrode can be reduced, so that the vibration load of each electrode can be reduced and vibration failure can be prevented.

Moreover , the slit which a solder | pewter does not get was formed in the secondary side electrode, the position of soldering was narrowed by the slit, and it positioned on the outer side of the slit. Since the solder does not get on the slit portion, the amount of solder on the secondary electrode can be reduced, so that the vibration load on the secondary electrode can be reduced, vibration failure can be prevented, and the occurrence of cracks and the like can be reduced. .

In addition to the above effects, soldering can be stably performed at a predetermined position such as the substantially central portion of the secondary electrode.

[Embodiment 1]
FIG. 1A is a top view of a piezoelectric transformer according to an embodiment of the present invention, and FIG. 1B is a bottom view of the same.

  In the figure, reference numeral 1 denotes a piezoelectric ceramic in the form of an elongated plate, and primary electrodes 2 and 3 are formed on the upper and lower surfaces of one half of the driving portion side by printing, respectively.

  Further, on the upper and lower surfaces of the outer end portion on the output portion side of the other half of the piezoelectric ceramic 1, a substantially rectangular secondary electrode 4 having a long side b and a short side c along the width direction a of the piezoelectric ceramic 1 is provided. 5 are formed by printing, and the piezoelectric transformer 6 is configured.

  A lead wire is connected to either one of the secondary side electrodes 4 and 5, but in this embodiment, inside the secondary side electrode 5 on the side to which the lead wire is connected, that is, on the primary side electrode 3 side. A feature is that an elongated, substantially rectangular slit 7 is formed along the long side b, and the outer end of the slit 7, that is, the outer end of the piezoelectric ceramic 1 from the slit 7 is used as a soldering portion.

  The slit 7 can be easily formed when the secondary electrode is printed.

  FIG. 2 shows a state in which the lead wire 8 is connected to the outside of the slit 7 of the secondary electrode 5 by solder 9.

  When the soldering positioning slits 7 are provided on the inner side in this way, no load is applied to the boundary between the polarized region and the non-polarized region, which are structurally weak in strength, as shown in FIG. In addition, the area of the soldering portion can be narrowed by the slit 7 and the portion of the slit 7 repels the solder 9 and the solder 9 does not get on, so the amount of the solder 9 is reduced. be able to.

  Therefore, the vibration load can be reduced, and various adverse effects associated with the vibration load such as efficiency reduction, abnormal heat generation, and damage due to cracking can be reduced or prevented.

  Moreover, if the slit 7 is provided inside the secondary side electrode 5, the amount of solder can be reduced, and soldering can be performed outside the polarization interface, and cracks and damage can be prevented.

  Further, due to the difference in the electrode pattern between the secondary electrode 5 provided with the slits 7 and the holes 12 and the secondary electrode 5 not provided with the slits 7 and the holes 12 and the like, Since it can be distinguished from the lower surface, the polarity of the primary side polarization of the piezoelectric ceramics 1 can be expressed by the secondary electrode 5 provided with the slits 7, the holes 12, and the like.

  As shown in FIG. 3, lead wires 10 and 11 are also connected by solder 9 to predetermined positions of the primary side electrodes 2 and 3, respectively.

  As is well known, the piezoelectric transformer 6 is housed in a box-shaped case (not shown) having an open bottom, and in the illustrated state, the lower surface side of the piezoelectric transformer 6 shown in FIG. A secondary-side lead wire 8 is connected to a secondary-side electrode 5 exposed to the outside and having a slit 7 on the lower surface side through solder 9.

  A similar slit 7 may be formed in the secondary side electrode 4 on the upper surface side.

[Embodiment 2]
FIG. 4 shows another embodiment of the present invention. This example is characterized in that at least one or more holes 12 are provided on both sides of the slit 7 in the length direction and toward the outer end of the secondary electrode 5.

  If the hole 12 is provided in this way, the solder position can be specified at a predetermined position such as the inner side surrounded by the slit 7, the hole 12, that is, the substantially central portion of the secondary electrode 5, etc. A diameter, a position, etc. can be stabilized more and the stable characteristic can be acquired.

  In addition, the number of the holes 12 provided on both ends of the slit 7 is not limited to the illustrated example. In addition, it is of course possible to use an elliptical shape, a long and narrow substantially rectangular slit, or other shapes, and these can be easily formed at the time of secondary electrode printing. The power generation section between the primary electrodes 2 and 3 of the piezoelectric ceramic 1 is polarized in the thickness direction, and the output section is polarized in the length direction. The characteristics can be changed by changing the polarization direction. Therefore, the slit 7 is formed in the secondary electrode 5 on one surface side of the piezoelectric ceramics 1 and the electrode on the other surface side has no slit.

[Embodiment 3]
In the third embodiment, the slit 7, the hole 12, and the like provided in the secondary electrode 5 according to the first and second embodiments are provided in at least one of the primary electrodes 2 and 3. Thereby, it can solder to a predetermined position with respect to the electrode in which the slit 7, the hole 12, etc. were provided.

  When the slit 7 and the hole 12 are provided in one of the primary side electrodes 2 and 3, or when the slit 7 and the hole 12 and the like are provided in both the primary side electrodes 2 and 3, the slit 7 and the hole 12 If the pattern to be formed is changed, the pattern of the electrodes is different between the primary side electrode 2 and the primary side electrode 3, so that the upper surface and the lower surface of the piezoelectric ceramic 1 can be distinguished, and the polarity of the polarization on the primary side of the piezoelectric ceramic 1 Can be expressed.

  When the slits 7 and the holes 12 are provided in the primary side electrodes 2 and 3, two slits 7 may be arranged in parallel, or the slits 7 may be arranged in parallel to the longitudinal direction of the piezoelectric ceramics 1. Good. In addition, there are various arrangements of slits 7 and holes 12.

(A) is a top view of the piezoelectric transformer of one Example of this invention, (b) shows the bottom view same as the above. The principal part explanatory drawing of one Example of this invention is shown. The side view of the state which connected the lead wire to the piezoelectric transformer which concerns on one Example of this invention is shown. The principal part explanatory drawing of the other Example of this invention is shown. The side view of the conventional piezoelectric transformer is shown. (A), (b) shows the state from which a solder position differs. (A), (b) shows explanatory drawing of the different solder diameter in the past. An example of polarization of a piezoelectric transformer is shown. The crystal direction of polarization on the secondary side is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piezoelectric ceramics 2, 3 Primary side electrode 4, 5 Secondary side electrode 6 Piezoelectric transformer 7 Slit 8 Lead wire 9 Solder 10, 11 Lead wire 12 Hole

Claims (1)

In the piezoelectric transformer, the piezoelectric ceramic includes a primary electrode for voltage input and a secondary electrode for voltage output.
The secondary electrode has a substantially rectangular shape having long and short sides along the width direction of the piezoelectric ceramic, and is soldered along the long side inside one of the secondary electrodes. A piezoelectric transformer characterized in that a slit for narrowing a region of the part is formed and the outside of the slit is a soldered part.

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