JPH0415644B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ultrasonic delay line, and particularly to an ultrasonic delay line in which the shape of the transducer is devised in order to reduce unnecessary signals.

[Prior art] Conventionally, one of the upper electrodes of an input/output transducer
A lead wire is bonded or fused to the portion using solder or conductive paste, and electrical signals are input and output to and from the ultrasonic delay line through the lead wire. 3 and 4 show partially enlarged side views of a conventional ultrasonic delay line transducer. An input/output transducer for electromechanical vibration conversion is attached to one side of the delay medium 7 made of glass or the like. The transducer is composed of a piezoelectric body 1 made of LiNbO ₃ crystal, PZT crystal, etc., and an upper electrode 2 and a lower electrode 3 attached to one surface of the piezoelectric body 1 and a surface opposite to the piezoelectric body 1. The transducer is attached to a delay medium 7 via a bonding layer 6 made of solder, conductive paste, or the like. 1 on top electrode 2
A lead wire 5 for inputting and outputting electric signals is fixed to the portion by adhesion or fusing with a conductive member 4 made of solder, conductive paste, or the like. The upper electrode 2 and the lower electrode 3 are made of a material with good electrical conductivity, such as gold, attached by a method such as plating, vapor deposition, or sputtering.

Conventionally, the mechanical vibration of the piezoelectric body 1 that occurs when driving a transducer has a component that propagates to the delay medium 7;
A portion of the electrically conductive member 4 propagates toward the electrically conductive member 4 .
It is known that there are components that are reflected by The component reflected by the conductive member 4 interferes with the component normally propagating to the delay medium 7, resulting in the generation of ultrasonic waves with different phases within the delay medium. Conventionally, in order to deal with the above problem, as shown in FIG. 3, sound absorbing materials 8 having different mechanical impedances are bonded onto the conductive member 4 to absorb mechanical vibrations propagating toward the conductive member 4. Alternatively, as shown in FIG. 4, a method has been taken in which the lower electrode 3 corresponding to the adhesive surface of the conductive member 4 is removed, but this increases the number of steps and has insufficient characteristics.

[Problems to be Solved by the Invention] The object of the present invention is to overcome the aforementioned drawbacks of the prior art.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and includes an input/output transducer for electromechanical vibration conversion attached to one surface of an ultrasonic delay medium. In the ultrasonic delay line, the lower electrode side surface of the piezoelectric body corresponding to the bonding surface of the conductive member for bonding lead wires bonded onto the upper electrode of the transducer is placed parallel to the bonding surface of the transducer. 1/ of the thickness of
Cut the transducer into a rectangular parallelepiped shape, or cut the transducer into a curved shape that is diagonal from the lower electrode side to the upper electrode side, or convex to the adhesive side. The cutout is filled with a bonding layer. The present invention provides an ultrasonic delay line characterized by the following.

[Function] In the present invention, the end of the transducer, which has been made thinner by removing the piezoelectric body and the lower electrode, is not only less likely to be excited even when an electric signal is input from the lead wire, but also vibrates at the same frequency as other parts. It is never excited. Furthermore, since the bonding layer filled between the delay medium and the cut-out piezoelectric body absorbs leaked mechanical vibrations, it has the effect of preventing further diffusion and propagation into the delay medium. In this way, the effect of suppressing unnecessary vibration components that diffusely reflect and propagate between the lead attachment portion, the adhesive surface, and the transducer is produced.

[Embodiments] Two embodiments of the present invention are shown in FIGS. 1 and 2. An input/output transducer for electromechanical vibration conversion is attached to one surface of the delay medium 7 made of glass or the like. The transducer is
It is composed of a piezoelectric body 1 made of LiNbO ₃ crystal, PZT crystal, etc., and an upper electrode 2 and a lower electrode 3 attached to one surface of the piezoelectric body 1 and an opposite surface thereof. The transducer is attached to a delay medium 7 via a bonding layer 6 made of solder, conductive paste, or the like. A lead wire 5 for inputting and outputting electrical signals is bonded or fused to a portion of the upper electrode 2 with a conductive member 4 made of solder, conductive paste, or the like. Upper electrode 2 and lower electrode 3
is made of an electrically conductive material such as gold attached by plating, vapor deposition, sputtering, or other methods.

FIG. 1 shows a rectangular parallelepiped-shaped cutout of the surface of the piezoelectric body 1 facing the lower electrode 3, which corresponds to the adhesive surface of the conductive member 4 attached to the upper electrode 2 of the transducer. The bonding layer 6 made of solder or conductive paste, etc., wraps around the notch when the transducer is crimped onto the delay medium 7, and
It tends to be thicker only in the notched part. Therefore, the mechanical vibration leaked from the vibrating part sandwiched between the upper electrode 2 and lower electrode 3 of the piezoelectric body 1 is absorbed,
This has the effect of preventing propagation into the delay medium 7. It is better if the bonding layer at the notch is tightly packed as shown in the figure. Therefore, the higher the height of the notch is, the more effective it is, but since the remaining part of the notch in the piezoelectric body 1 is likely to break when the transducer is crimped, the height of the notch is The thickness is preferably about 1/4 to 1/2 of the thickness of 1. Incidentally, since the bonding layer 6 at the cutout portion is thicker than other portions, it also has the advantage that mechanical vibrations are difficult to propagate. In FIG. 2, the piezoelectric body 1 is obliquely removed, and mechanical vibrations are reflected at the oblique portion and attenuated within the piezoelectric body 1 so as not to propagate into the delay medium 7. The bonding layer 6 corresponding to the diagonal notch is partially thickened as shown in the embodiment of FIG. It has the effect of making it so. The slope of the notch may be formed into a curved surface that is convex toward the bonding layer 6 side. In this case, the mechanical vibrations reflected from the slope are not diffusely reflected into the piezoelectric body 1, and unnecessary signals are generated. It is effective in suppressing

Furthermore, in the embodiments of FIGS. 1 and 2, between the bonding layer 6 and the remaining cutout portion of the piezoelectric body 1,
A sound absorbing material such as epoxy resin may also be provided.

[Effects of the Invention] The present invention forms a non-driving part in the transducer by cutting out the lower electrode side surface of the piezoelectric material corresponding to the adhesive surface of the conductive member of the transducer, and the conductive member This has the excellent effect of suppressing the occurrence of unnecessary mechanical vibrations that are reflected by the oscilloscope and propagated into the delay medium. In addition, there is no need to perform secondary processing such as adhering materials with different mechanical impedances to the conductive member in order to absorb mechanical vibrations propagated to the conductive member, so the process can be simplified. It also has

[Brief explanation of drawings]

1 and 2 show two embodiments of the present invention, each showing a partially enlarged side view of a transducer of an ultrasonic delay line, and FIGS. 3 and 4 show views of a conventional example, FIG. 3 is a partially enlarged side view of a transducer of an ultrasonic delay line, respectively; DESCRIPTION OF SYMBOLS 1... Piezoelectric body, 2... Upper electrode, 3... Lower electrode, 4... Conductive member, 5... Lead wire, 6...
Bonding layer, 7...delay medium.

Claims (1)

[Claims] 1. In an ultrasonic delay line in which an input/output transducer for electromechanical vibration conversion is attached to one side of an ultrasonic delay medium by a bonding layer, a lead bonded onto the upper electrode of the transducer. The lower electrode side surface of the piezoelectric body corresponding to the bonding surface of the conductive member for wire bonding is cut out parallel to the bonding surface by about 1/4 to 1/2 of the thickness of the transducer in the shape of a rectangular parallelepiped. Alternatively, the transducer is cut out obliquely from the lower electrode side surface to the upper electrode side surface, or in a curved shape convex to the bonding surface side, and the cutout portion is filled with a bonding layer. An ultrasonic delay line characterized by: 2. Claim 1, in which a sound absorbing material such as epoxy resin is provided between the bonding layer and the notch.
Ultrasonic delay line as described in section.