JPH0218595Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a long-side longitudinal vibrator comprising a rod-shaped piezoelectric diaphragm with excitation electrodes attached to the longitudinal side surfaces thereof.

[Prior art]

Conventionally, in this type of long-side longitudinal vibrator, there is a difference in series resonance resistance (hereinafter abbreviated as CI) when the package is placed in a vacuum or at normal pressure, but this is particularly true due to photolithographic processing. The difference is large in ultra-small high-frequency vibrators such as those formed by For example, the vibrator shown in FIG.
The diaphragm 11 has counter electrodes 1 on both supporting sides of the diaphragm 11.
3 is attached. Its tip has a flat shape perpendicular to the longitudinal direction and has a vibration frequency of d ₁ at a vibration frequency of 1 MHz.
×d ₂ = 0.2 × 0.08 mm ^{2 It has an area of about 2} , but its CI is about 300 to 1000 Ω in a vacuum, but it is 4 to 5 kΩ at normal pressure, which is about 3 to 4 kΩ and can be ignored. There will be no difference. Therefore, in order to obtain a vibrator with a low CI, it is essential to store it in a vacuum package.In order to provide a vibrator that is cheaper in terms of the degree of freedom of the package and the hassle of assembly and adjustment processes, etc. It was becoming an obstacle.

[Purpose and structure of the invention]

The present invention was devised in view of these circumstances, and its purpose is to provide a long-side longitudinal vibrator that can obtain a CI as low as in a vacuum even at normal pressure.

In order to achieve this purpose, the present invention
It is a rod-shaped diaphragm with both ends sharpened.
Hereinafter, the present invention will be explained in detail using the illustrated embodiments.

〔Example〕

FIG. 2 is a perspective view showing an embodiment of the present invention. This embodiment is an example in which the diaphragm 21 and the support body 22 are integrally formed from a thin crystal plate by photolithography processing as in FIG.
A counter electrode 23 is attached to the side surface in the long side direction of 1. The support body 22 supports the diaphragm 21 perpendicularly to the side surface to which the excitation electrode 23 is attached.
2a is a support arm, and 22b is a support base. Also,
22c is a recess provided to reduce acoustic leakage to the support. The upper excitation electrodes 23 are connected to the lead-out portions 23 through the support arms 22a, respectively.
a are drawn out to the front and back sides of the support base 22b.

Here, the diaphragm 21 has a planar tip in the conventional diaphragm 11 shown in FIG. The slanted surface has a sharply pointed shape.

As is well known, a long-side longitudinal vibrator has a vibration mode that expands and contracts in the long-side direction, so when it vibrates,
Air resistance against the tip surface is thought to have a particularly large effect on the CI, and in fact, the first
In a vibrator like the one shown in the figure, when an object is brought close to the tip of the diaphragm while an excitation voltage is applied between the electrodes to make it vibrate, the CI changes periodically, causing air vibrations near the end. It is confirmed that there is a standing wave.

Therefore, in this case, as shown in FIG. 2, the area of the tip surface of the diaphragm should be reduced, especially
Sharpening the tip into a so-called streamlined shape reduces air resistance and is extremely effective in reducing CI under normal pressure, making it possible to obtain the same performance as using a vacuum package.

The above explanation uses the term "air" resistance, but when a vacuum package is not used in a piezoelectric vibrator, a package filled with an inert gas such as nitrogen gas is often used rather than so-called air. It goes without saying that the above explanation can be similarly applied to the case where such a gas is filled.

In addition, the explanation was given using a vibrator formed integrally with a support body by photolithography processing as an example, but this is particularly true for ultra-small vibrators that can only be formed by photolithography. This is because the problem of increased CI due to "air" resistance containing such gas is significant, and does not indicate that the scope of application of the present invention is limited to such.

In the above-described embodiment, since it is easy to form by photolithography, the diaphragm 21 has a configuration in which only the main surface to which the electrode is attached at the tip 21a is sloped, and the tip is linear. It goes without saying that the ivy may have four inclined surfaces and a dotted tip as shown in FIG. 3, for example.

Furthermore, although the explanation was given using a crystal resonator as an example, the present invention is generally applicable to resonators made of lithium niobate, lithium tantalate, etc., and other rod-shaped piezoelectric resonators having a similar long-side longitudinal vibration mode. It goes without saying that it can be done.

[Effect of idea]

As explained above, according to the present invention, by sharpening the tip of the rod-shaped longitudinal vibrator on the long side, CI can be reduced to the same extent even at normal pressure as in a vacuum, so it is not necessary to use a vacuum package. This eliminates the need for packaging, which has advantages in terms of flexibility in package selection and simplification of assembly and adjustment processes.
It is possible to provide a cheaper vibrator and is extremely useful, especially in ultra-small vibrators.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of the configuration of a conventional long-side vertical vibrator, and FIG. 2 is a perspective view showing an example of the present invention.
FIG. 3 is a perspective view showing another embodiment of the present invention. 21... Piezoelectric diaphragm, 21a... Tip, 22
... Support body, 23 ... Excitation electrode.

Claims (1)

[Scope of utility model registration request] In a long-side vertical vibrator in which electrodes for long-side vibration excitation are attached to the side surfaces of a rod-shaped piezoelectric diaphragm in the long-side direction, both ends of the piezoelectric diaphragm are inclined at acute angles with respect to the long-side direction. A long-side longitudinal vibrator characterized by having a convex configuration with a sloped surface.