JPH01157199A - Frequency adjusting method for supersonic transmitter and receiver - Google Patents

Abstract

PURPOSE:To ease frequency adjustment by deleting one part of the inside taper face of a linking part between a case top panel part and a case side wall part and executing the adjustment of a frequency. CONSTITUTION:An arbitrary spot 16 is deleted in a taper face 13a of a taper shaped linking part 13, which unitedly links a plain case top panel part 2 to have a constant thickness and a case inner wall part 12 to be extended in a rectangular direction to the case top panel part 2 at the position of a larger diameter than this case top panel part 2. As this result, the node point of bending oscillation in a piezoelectric oscillator 3 is moved to outside and a diameter is caused to be practically large of a diameter D2 after the deleting to a diameter D1 of the top panel part 2 which relates to the oscillation before the deleting. Then, the central frequency, which relates to the sensitivity and sound pressure of a supersonic is adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a frequency adjustment method for an ultrasonic transducer using a piezoelectric vibrator.

[Conventional technology] An example of an ultrasonic transducer is shown in FIG.

The ultrasonic transducer is used as a car pack sensor, and has a cylindrical case l. A piezoelectric ceramic vibrator 3 is bonded to the inside of the top surface part 2 of the case 1 to form a vibrating part, and an opening 4 is formed on the other side of the case 1, and the opening 4 is closed with a sealing member 5.6 in between. Terminal 7.8
It is closed by a terminal plate 9 provided with. 10. II is a lead wire connected to the terminal 7.8, the other end of the lead wire IO is connected to the piezoelectric ceramic vibrator 3, and the lead wire j
The other end of l is connected to the top surface part 2. The top surface part 2 forming a part of the vibrating part has a thickness equal to that of the peripheral wall part 12 in order to reduce the influence of support from the peripheral wall part 12 of the case 1. Constructed thinner.

By the way, there are almost always variations and errors in the case l and the piezoelectric ceramic vibrator 3 during manufacturing, and due to these variations and errors or due to user requests, the center of sensitivity and sound pressure of ultrasonic waves may be affected. Frequency may need to be adjusted.

Such adjustment is performed when the frequency of this type of ultrasonic transducer is adjusted to the thickness of the top surface 2 of the case. Since it is proportional to the sum of the thickness of the piezoelectric ceramic vibrator 3 and the thickness of the piezoelectric ceramic vibrator 3, conventionally, after the piezoelectric ceramic vibrator 3 is attached to the top plate part 2, the thickness of the case top part 2 is 1. In order to lower the frequency, a method is adopted in which the top surface part 2 of the case is shaved off from the outside to reduce the thickness tl (for example, see Japanese Patent Application Laid-Open No. 50-83012). .

However, when cutting the outside of the case top 2, it is necessary to finish the outside surface of the case top 2 sufficiently flat so that the sensitivity and sound pressure of the transducer itself will not decrease due to scraping. required a high level of skill.

In addition, in the case of a drip-proof transducer used outdoors, such as a back sensor in an automobile, the outer surface of the case l is treated with anti-corrosion and insulation treatments (for example,
Case 1 is made of aluminum and the outer surface is anodized), so if you scrape off the outside of top panel 2, it will prevent rust.
The disadvantage is that the insulation effect is lost.

[Object of the Invention] Therefore, the present invention provides an ultrasonic transducer using this type of piezoelectric vibrator, in which the frequency can be adjusted by extremely simple machining without cutting the outside of the top surface of the case. The purpose is to

[Summary of the Invention] The present invention utilizes bending vibration of a transducer or a piezoelectric vibrator having this type of structure, and the center frequency related to sensitivity and sound pressure is proportional to the thickness Q++tt), while the case top Focusing on the fact that the diameter of the surface is inversely proportional to the square of the diameter of the surface, at least the inner surface of the connecting portion that integrally connects the case top surface and the case peripheral wall is formed into a tapered surface, and a part of this tapered surface is deleted. This is characterized in that the frequency is adjusted by substantially increasing the diameter of the top surface of the case.

[Example] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The present invention will be explained in detail with reference to FIGS. 2 and 3.

In FIGS. 2 and 3, parts corresponding to those in FIG. 1 are designated by corresponding reference numerals, and redundant explanation will be omitted.

In FIG. 2, the case 21 has an upper part shaped like a truncated cone and a lower part shaped like a cylinder. That is, the case top surface part 2 has a constant thickness and is flat, and the case peripheral wall part 12 extends in a direction perpendicular to the case top surface part 2 at a position larger in diameter than the case top surface part 2.
A tapered connecting portion 13 is formed by integrally connecting these.

The connecting portion 13 forms an outer tapered surface 13 b and an inner tapered surface 13 a extending from the inner surface of the case top surface section 2 to the inner surface of the case peripheral wall section 12 . Preferably, the case top portion 2
The thickness t of the connecting portion 13 and the thickness L3 of the connecting portion 13 are set to be equal, for example, 0.6 mm. On the other hand, the thickness t of the case peripheral wall portion 12. has a thickness of 1.5 mm to avoid damping the vibration of the vibrating part.
．． 1. The thickness is selected to be about 5 times thicker than that of , that is, about 3 mm. However, if there is a request for processing or strength, the thickness L3 of the connecting portion 13 may be changed to the thickness 1. It may be larger.

On the other hand, in FIG. 3, the case l has a cylindrical shape, and only the inside of the connecting part 13 that integrally connects the case top surface part 2 and the thick case peripheral wall part 12 is formed into a tapered surface 13a. Further, the terminal board provided with the terminals 7 and 8 is fixed to an annular step 14 formed in the opening 4 of the case with an adhesive 15 or the like.

The terminals 7.8 are attached to the case peripheral wall 12 in order to provide strength.
It is located below. The terminal 7 is connected to an electrode on one side of the piezoelectric vibrator 3 via a lead wire 10.

Further, a terminal 8 which is insulated from the terminal 7 is connected to the inner surface of the case peripheral wall 12 via a lead wire 11, and is connected to the other electrode of the piezoelectric vibrator 3 through the case 1.

In the ultrasonic transducer shown in Figs. 2 and 3 above, when adjusting the center frequency r related to the ultrasonic sensitivity and sound pressure, as shown in Fig. 4, the taper surface is cut using a cutting tool inside the case. Delete arbitrary part 16 of 13a. If the case 1 is made of aluminum, it is soft and can be easily cut. By cutting, the node point of the bending vibration of the piezoelectric vibrator 3 moves outward. While the diameter of the top surface portion 2 is related to vibration before cutting, the diameter becomes substantially larger after cutting. This allows the frequency f
decreases.

The cutting amount and frequency change Δr at a predetermined cutting location are determined in advance.
By determining the relationship, it is possible to obtain an ultrasonic transducer with a desired frequency through uniform processing steps. This is suitable for lot production according to user requests. In addition,
In the above embodiment, an ultrasonic wave transducer is used, but the present invention can be similarly applied to a device having only a single function of a wave transmitter or a wave receiver.

Note that if the piezoelectric vibrator is bonded to almost the entire inside of the case peripheral wall (for example, as shown in Fig. 4), as shown in the cutting point 16 in Fig. 4, In this regard, the base of the tapered surface can be cut without damaging the piezoelectric vibrator, and in this sense too, cutting the tapered surface formed as in the embodiment has a great advantage.

[Effects] As described above, according to the present invention, by cutting a part of the inner tapered surface of the connecting portion between the case top surface portion and the case peripheral wall portion, the frequency can be reduced.
By making one adjustment, the frequency can be easily adjusted by the extremely simple process of cutting the taper, and the cutting process on the outside of the top of the case, which requires a high level of skill as in the past, is no longer necessary. This eliminates the need for consideration of rust prevention, insulation, etc.

[Brief explanation of the drawing]

Fig. 1 is a schematic cross-sectional configuration diagram of an ultrasonic transducer to which the conventional frequency adjustment method is applied, and Figs. 2 and 3 are schematic diagrams showing ultrasonic transducers to which the present invention is applied. The cross-sectional structure diagram and FIG. 4 are explanatory diagrams related to frequency adjustment. l...Case, 2...Top section, 3 Piezoelectric vibrator, 4...
...Opening, 9...Terminal plate, 12...Peripheral wall part, 13.
... Connecting portion, 13a... Tapered surface. Patent applicant: Murata Manufacturing Co., Ltd. Agent: Patent attorney: Two idiots, Figure 1, Side 2, Figure 4, Figure 4

Claims (1)

[Claims] (1) has an opening closed by a terminal plate on one side, and has a thin top surface portion whose peripheral edge is connected to the peripheral wall portion on the other side;
A method for adjusting the frequency of an ultrasonic transducer in which a piezoelectric vibrator is attached to the inside of the top surface of a case in which the inner wall surface of the joint between the top surface and the peripheral wall is a tapered surface, the method comprising: A method for adjusting the frequency of an ultrasonic transducer, characterized in that the frequency is adjusted by partially removing the tapered surface of the connecting portion.