JPH0758875B2 - Piezoelectric resonator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a structure of a piezoelectric resonator, particularly a fork type,
The present invention relates to improvement of a resonator called a tuning fork type piezoelectric resonator.

[Prior art]

FIG. 4 shows an example of a conventional fork-type piezoelectric resonator as described above. FIG. 4 (a) is a perspective view seen from the front side.
FIG. 3B is a perspective view seen from the back surface side.

Such a piezoelectric resonator 1 has slits along the longitudinal direction of the piezoelectric substrate 2 on the symmetrical center line of the piezoelectric substrate 2 which is formed in a substantially right-angled quadrangular shape in a plan view so as to facilitate cutting from the mother substrate. 3 are formed on the surface side of the piezoelectric substrate 2 shown in FIG.
The V-shaped first electrode 4 and the second electrodes 5, 5 are formed at a predetermined distance from the first electrode 4, and the first electrode 4 is formed on the back surface side shown in FIG. 4 (b). The third electrode 6 is formed so as to face both the second electrode 5 and the second electrode 5 in common.

The second electrodes 5, 5 are connected to the common electrode 9 via the lead terminals 7a, 7b soldered to the legs 5a, 5b, and the legs 4a of the first electrode 4 are connected via the lead terminals 8. It is connected to the electrode 10. The third electrode 6 is in an open state, that is, a state in which nothing is connected.

In such a piezoelectric resonator 1, the common electrode 9 and the electrode 10 are
When an excitation signal is applied between the first electrode 4 and the third electrode,
An electric field directed to the second electrode 5 via the electrode 6 and an electric field in the opposite direction are alternately formed, and the portions separated by the slit 3 vibrate such that the width of the slit 3 opens or closes.

In the piezoelectric resonator shown in FIG. 4 as described above, its vibration frequency is adjusted according to the length of the slit 3 and the width of the portion where the first electrode 4 and the second electrode 5 are formed. It

[Problems to be solved by the invention]

As described above, in the conventional fork-type piezoelectric resonator, the size of the vibrating part has a great influence on the vibration frequency, and generally, in order to increase the vibration frequency, it is necessary to reduce the size of the vibrating part. Are known.

However, in the piezoelectric resonator 1 of the type in which the lead terminals 7a, 7b, 8 are soldered as shown in FIG. 4, in terms of workability of soldering, there is a limit in reducing the size of the soldered portion. There is. In this regard, it is possible to configure a deformed piezoelectric resonator so as to keep the soldered portion large and reduce the vibrating portion, but such a deformed piezoelectric resonator is There is a problem that it is difficult to cut out, and the area of the discarded portion of the substrate becomes large due to the deformed structure, which promotes cost increase.

Therefore, an object of the present invention is to improve the vibration frequency in such a piezoelectric resonator while keeping the shape of the piezoelectric substrate in a substantially right-angled shape in plan view so that it can be easily cut out from the mother substrate. .

[Means for solving problems]

In order to achieve the above-mentioned object, the main means adopted by the present invention is to form three slits substantially parallel to one side of a piezoelectric substrate having a substantially right-angled quadrangular shape on a plane, and to form one side of the piezoelectric substrate. On one side, a first electrode is formed along both side edges of the central slit, and a pair of second electrodes is formed along the side edges on the first electrode side of both outside slits with a distance from the first electrode. Then, a third electrode is formed at a portion sandwiched between the both outer slits on the other surface side of the piezoelectric substrate and facing both of the first and second electrodes in common, and A pair of fourth electrodes connected to the respective second electrodes are formed on the non-vibrating portion on the one side of the piezoelectric substrate and outside the both outer slits, and the non-vibrating portion of the piezoelectric substrate is formed. And the other side facing away from the fourth electrode on the one side. Fifth to portions connected to the first electrode
This is a piezoelectric resonator having a point of forming electrodes.

[Action]

In the above-mentioned piezoelectric resonator, the central slit corresponds to the slit 3 shown in FIG. 4, and the portion sandwiched by the slits provided outside thereof constitutes the piezoelectric resonator body. And
The second electrode formed on the piezoelectric resonator body is connected to one of a pair of fourth electrodes formed on a portion further outside the outer slit, and is formed along the central slit. One electrode is connected to the fifth electrode, and by fixedly supporting the fourth electrode portion and the fifth electrode portion, the piezoelectric resonator main body portion is kept in a floating state and free vibration is possible. Can be

By applying an excitation signal to the fourth electrode and the fifth electrode,
The portion of the piezoelectric resonator body vibrates. Since the portion of the piezoelectric resonator main body is supported by the portion provided with the fourth electrode and the fifth electrode, it can be formed to have free dimensions by itself, and a high resonance frequency can be obtained.

〔Example〕

Next, an embodiment in which the present invention is embodied will be described with reference to FIGS. 1 to 3 to provide an understanding of the present invention. FIG. 1 shows a piezoelectric substrate of a piezoelectric resonator according to an embodiment of the present invention. FIG. 1 (a) is a perspective view seen from the front side, and FIG. 1 (b) is the back side. FIG. 2 is a perspective view, FIG. 2 is a plan view showing a state in which the piezoelectric substrate shown in FIG. 1 is housed in a holding substrate, and FIG. 3 is a chip-like structure obtained by further covering the holding substrate shown in FIG. 2 with a lid. It is a perspective view which shows the state used as a piezoelectric resonator.

The following examples are merely specific examples of the present invention, and do not limit the technical scope of the present invention.

Moreover, the same reference numerals are used for the elements common to the conventional piezoelectric resonator shown in FIG. 4, and the description thereof will be omitted.

As shown in FIG. 1, the piezoelectric substrate 11 according to this embodiment is
In order to make it easy to cut out from the mother substrate, it is formed in a substantially rectangular shape in a plan view. On the symmetric center line of the piezoelectric substrate 11 and on one side, the slit 3 shown in FIG.
A slit 3 similar to that is formed. Further, on both sides of the slit 3, outer slits 12a and 12b which are parallel to the slit 3 and are longer than the slit 3 are formed.

The portion sandwiched between the outer slits 12a and 12b is the piezoelectric resonator body 13.

Therefore, a U-shaped first electrode 4 is formed on the one side of the surface of the piezoelectric substrate 11 shown in FIG. 1A along both side edges of the central slit 3. 4 and the first slit of the pair of outer slits 12a, 12b at a distance from each other.
The second electrodes 5, 5 are formed along the side edge on the electrode 4 side. Then, as shown in FIG. 1 (b), on the back side of the piezoelectric resonator body 13, a portion sandwiched between the pair of outer slits 12a and 12b, that is, the first electrode 4 and the second electrode. The third electrode 6 is formed at a portion facing both 5 and 5 in common.

In addition, a portion of the piezoelectric substrate 11 outside the outer slits 12a, 12b on the front surface side shown in FIG. Part 1
Fourth electrodes 14, 14 connected via 5, 15 are formed.

Further, the fifth electrode 17 connected to the first electrode 4 via the connecting portion 16 is a portion excluding the vibrating portion such as the piezoelectric resonator body 13, and the fourth electrode on the one side. It is formed on the other side portion facing away from 14,14.

Although the piezoelectric substrate 11 as described above is configured to have a certain size, the piezoelectric resonator main body which is the vibrating portion.
By appropriately considering the formation positions of the slits 4 and 12a, 12b, 14 can be formed to have an arbitrary size, either extremely small or large.

FIG. 2 shows an example of a holding substrate for holding the piezoelectric substrate 11 thus configured and supplying an excitation signal.

In this case, the holding substrate 18 is formed in a right-angled quadrangular shape slightly larger than the piezoelectric substrate 11, and a pair of substantially parallel projecting electrodes 19 a and 19 b are formed with a gap 20 therebetween. As shown in FIG. 2, one of the protruding electrodes 19a, 19b is provided with a recess so that the piezoelectric resonator body 13 does not come into contact with the protruding electrode 19a when the piezoelectric substrate 11 is placed on the holding substrate 18. 21 are formed.

Since the projecting electrodes 19a and 19b project slightly in the direction perpendicular to the plane of the drawing from the plane of the gap 20, the piezoelectric substrate 11 is not
As shown in the figure, when it is superposed on the central portion of the holding substrate 18,
The piezoelectric substrate 11 is floated from the surface of the holding substrate 18,
In particular, the portion of the piezoelectric resonator main body 13 is in a completely floating state except that it is connected to the piezoelectric substrate 11 via the leg portions 22 thereof.

Therefore, solder the fourth electrodes 14, 14 to the protruding electrode 19a.
23a, 23b are fixed to the holding substrate 18, and the fifth electrode 17 is soldered 23c to the protruding electrode 19b and fixed to the holding substrate 18, the piezoelectric substrate 11 is held by the soldering 23a, 23b, 23c. It is completely held at 18 and has protruding electrodes 19a and 19b.
When an excitation signal is applied to, the portion of the piezoelectric resonator body 13 vibrates at its resonance frequency.

When actually using the above-described piezoelectric resonator, in order to protect the piezoelectric substrate 11 from moisture and dust, the piezoelectric substrate 11 is covered with a cover 24 made of plastic or the like by adhesion, and the protruding electrode 19
It is used by soldering a and 19b to the printed circuit board.

In the above embodiment, the fourth electrode 14 is set at the corner of the piezoelectric substrate 11, and the fifth electrode 17 is formed on the portion opposite to the fourth electrodes 14 and 14, but such an electrode is formed. It is also possible to form it on the back surface side through an electrode (not shown) formed at the end portion of.

〔The invention's effect〕

According to the present invention, as described above, three parallel slits are formed from one side of a piezoelectric substrate having a rectangular shape in a plane.
On one side of the piezoelectric substrate and on the one side, a first electrode along both side edges of the central slit, and a side edge on the first electrode side of both outer slits spaced apart from the first electrode. A pair of second electrodes are formed along the piezoelectric substrate, and the portion sandwiched between the outer slits on the other surface side of the piezoelectric substrate is the first electrode.
A third electrode is formed at a portion commonly facing both the first and second electrodes, and each of the first and second electrodes is provided on a non-vibrating portion on one side of the piezoelectric substrate and further outside the slits on the outside. A pair of fourth electrodes respectively connected to the two electrodes are formed, and a first electrode is formed on a non-vibrating portion of the piezoelectric substrate on a side of the other side facing away from the fourth electrode of the one side. Since it is a piezoelectric resonator formed with a fifth electrode connected to, only the piezoelectric resonator main body, which is the vibrating portion while the piezoelectric substrate is kept in a substantially rectangular shape in plan view so that it can be easily cut out from the mother substrate. Can be downsized and its resonance frequency can be increased. Further, with the above-described configuration, the distance between the fourth and fifth electrodes corresponding to the input / output electrodes can be maximized, and the third electrode can be minimized with respect to the front and back surfaces of the piezoelectric substrate. It is possible to avoid the third electrode and the fourth and fifth electrodes and the connecting portion connected to them from directly facing each other, and it is possible to suppress the generation of unnecessary stray capacitance and stabilize the characteristics. is there.

[Brief description of drawings]

FIG. 1 shows a piezoelectric substrate of a piezoelectric resonator according to an embodiment of the present invention. FIG. 1 (a) is a perspective view seen from the front side thereof, and FIG. 1 (b) is seen from the back side thereof. FIG. 2 is a plan view showing a state in which the piezoelectric substrate shown in FIG. 1 is housed in a holding substrate, and FIG. 3 is a chip-shaped piezoelectric resonance in which the holding substrate shown in FIG. 2 is further covered. FIG. 4 is a perspective view showing a state where it is made into a child, FIG. 4 shows a piezoelectric substrate constituting a conventional piezoelectric resonator, FIG. 4 (a) is a perspective view seen from the surface side, and FIG. It is the perspective view seen from the back side. [Explanation of symbols] 3 ... central slit, 4 ... first electrode 5 ... second electrode, 6 ... third electrode 11 ... piezoelectric substrate 12a, 12b ... outer slit 13 ... piezoelectric resonator body 14 …… 4th electrode, 17 …… Fifth electrode 18 …… Holding substrate 19a, 19b …… Projecting electrode 20 …… Gap, 21 …… Concave 22 …… Legs 23a, 23b, 23c …… Soldering 24… …cover.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jiro Inoue 2 26-10 Tenjin Tenjin, Nagaokakyo-shi, Kyoto Murata Manufacturing Co., Ltd. (56) Reference JP-A-51-24190 (JP, A)

Claims (1)

[Claims] 1. A piezoelectric substrate having a quadrangular rectangular shape in a plane, and three parallel slits are formed from one side of the piezoelectric substrate. One side of the piezoelectric substrate is provided on one side of the piezoelectric substrate along both side edges of a central slit. A first electrode and a pair of second electrodes formed along the side edges on the first electrode side of both slits on the outer side of the first electrode, and the outer side of the other surface side of the piezoelectric substrate. A third electrode is formed in a portion sandwiched between both slits of the piezoelectric substrate, the third electrode being formed at a portion commonly facing both the first and second electrodes, and the one side of the piezoelectric substrate and the outer side of the piezoelectric substrate. A pair of fourth electrodes connected to the second electrodes are formed on the non-vibration portion further outside of both slits.
A piezoelectric resonator in which a fifth electrode connected to the first electrode is formed on a portion of the non-vibration portion of the piezoelectric substrate, which is on the other side facing away from the fourth electrode on the one side.