JP3320192B2 - Surface acoustic wave converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface acoustic wave converter in which a rectangular piezoelectric substrate is provided on a metal base, and comb-shaped input and output electrodes are formed on the piezoelectric substrate so as to face each other. .

[0002]

General description of the technical field according to the present invention: As shown in FIG.
0, an input electrode 11 and an output electrode 12 are formed facing each other, a high-frequency signal from a high-frequency power supply 13 is converted into a surface acoustic wave by the input electrode 11 and propagated on the piezoelectric substrate 10,
A surface acoustic wave converter is provided which converts the propagated surface acoustic wave into an electric signal again by the output electrode 12 and supplies the electric signal to the load 14, thereby obtaining a signal of a desired frequency band whose band is limited. The input electrode 11 has a plurality of comb teeth 1
Comb parts 11a1, 11b1 same as 1a1, 11b1
And a pair of comb-shaped electrodes 11a and 11b each including a connecting bar 11a2 and a connecting bar 11b2. The output electrode 12 also has a plurality of comb teeth 12a1, 12b1.
And a plurality of comb-shaped electrodes 12a and 12b, which are composed of connecting bar portions 12a2 and 12b2 respectively connecting the plurality of comb-shaped portions 12a1 and 12b1. If necessary, a sound absorbing agent 15, 16 may be provided on the piezoelectric substrate 10 on the side opposite to the opposite side of the input electrode 11 and the output electrode 12.
Is applied.

[0003] The surface acoustic wave converter thus configured is:
As shown in FIGS. 8 and 9, the lower surface of the piezoelectric substrate 10 is adhered to the conductive metal base 20 with an adhesive, and the connecting bar portion 11a2 of each of the comb-like electrodes 11a and 11b (input electrode 11). , 11b2 are metal conductive wires 21, 22
Through the metal base 20 in an airtight manner,
It is connected to the upper end surfaces of the lead pin 23 and the ground pin 24 protruding upward. Each comb-shaped electrode 12a, 12b
The connecting bar portions 12a2 and 12b2 of the (output electrode 12) also pass through the metal base 20 through metal conductive wires 25 and 26 in a gas-tight manner and protrude onto the base 20. It is connected to the end face. Then, the cap 29 over the metal base 20
Is hermetically bonded to the base 20 so as to cover the piezoelectric substrate 10 from above. Although the ground pins 24 and 28 are not insulated from the metal base 20, the lead pins 23 and 27 and the metal base 20 are glass insulators 23a and 27a (only 27a is shown).
Insulated by

[0004]

2. Description of the Related Art Conventionally, in such a surface acoustic wave conversion device, as shown in FIGS. 10 to 13 in an enlarged manner, the surfaces of connecting bar portions 11a2 and 11b2 of input electrode 11 and lead pin 23 and ground pin 24 are formed. Both ends of the metal conductive wires 21 and 22 are bonded to the respective upper end surfaces, and the connecting bar portions 12a2 and 1 of the output electrode 12 are connected.
Both ends of metal conductive wires 25 and 26 were bonded to the surface of 2b2 and the upper end surfaces of lead pin 27 and earth pin 28, respectively. FIG. 10 uses an apodized (weighted) electrode as the input electrode 11 and the output electrode 1
A regular electrode is used as 2 and both electrodes 11 and 1 are used.
This shows a conventional example in which a shield electrode 17 is provided between two electrodes and both ends of the electrode 17 are connected to a metal base 20 via conductive wires 17a and 17b. FIG. 11 shows an input electrode 11 and an output electrode 12 in the surface acoustic wave conversion device of FIG.
1 shows a conventional example in which the size and the shape of each of them are different. FIG. 12 shows that an apodized electrode is used for both the input electrode 11 and the output electrode 12 and that both electrodes 11 and 12 are used.
This shows a conventional example in which a multistrip coupler (MSC) 18 is provided therebetween. FIG. 13 shows a conventional example in which the size and shape of the input electrode 11 and the output electrode 12 in the surface acoustic wave conversion device of FIG. 12 are different.

[0005]

However, in the above-mentioned conventional device, the transducer portion including the piezoelectric substrate 10, the input electrode 11, the output electrode 12, and the like has a required frequency band,
The package varies depending on the performance and the like. On the other hand, although various packages are prepared, they are not prepared corresponding to the sizes of all the converter parts. Therefore, the length of the conductive wires 21, 22, 25, and 26 may be extremely long, and the wire may be cut or peeled off due to a decrease in the tensile strength of the wire, or a short circuit may occur due to the slack of the wire. Therefore, there is a problem that the frequency characteristics are deteriorated, the production cost is increased due to wasted wire, and the workability is deteriorated. Further, acoustic reflection occurs at the connecting bar portions 11a2, 11b2, 12a2, 12b2 and the wire boding portion,
The frequency characteristics, especially the rising characteristics and the stop band characteristics, are deteriorated (see FIG. 14).

SUMMARY OF THE INVENTION The present invention has been made to address the above problems, and an object of the present invention is to provide a surface acoustic wave conversion device which solves the above problems.

[0007]

In order to achieve the above-mentioned object, a structural feature of the present invention is that each of the connecting bars of the input electrode has a piezoelectric substrate on each of the outer sides thereof which is orthogonal to the side end face of the piezoelectric substrate. A pair of input electrode terminal portions are provided at positions equidistant from the end surface to be connected, and each of the input electrode terminal portions is extended through a pair of connection bar extension portions each extending at a predetermined acute angle from each connection bar portion of the input electrode on the piezoelectric substrate. The input electrode terminal portion and the connection bar portion of the input electrode are connected to each other, and a position equidistant from an end surface orthogonal to the side end surface of the piezoelectric substrate on each piezoelectric substrate outside each connection bar portion of the output electrode. And a pair of output electrode terminals are provided on the piezoelectric substrate through a pair of connection bar extensions respectively extending at a predetermined acute angle from the connection bars of the output electrodes on the piezoelectric substrate. Electrode The connection bar portions are connected to each other, and a pair of input electrode pins and a pair of input electrode terminal portions are arranged in a straight line, and each input electrode pin and each input electrode terminal portion are connected by a conductive wire. In addition, a pair of output electrode pins and a pair of output electrode terminals are arranged on a straight line, and each output electrode pin and each output electrode terminal are connected by a conductive wire.

[0008]

In the present invention constructed as described above, the input and output electrode terminal portions are provided on the piezoelectric substrate outside each of the connection bar portions of the input and output electrodes, respectively. Since the terminal portion and the input and output electrode pins are connected by conductive wires, the piezoelectric substrate 10, the input electrode 11, and the output electrode 1 of various sizes are provided.
Even when the converter portion composed of 2 or the like is mounted on a package of a predetermined size, the length of the conductive wire can be reduced to a predetermined short length. Therefore, it is possible to solve the problems of wire breakage and wire peeling, deterioration in frequency characteristics, increase in manufacturing cost, and deterioration in workability due to the longer conductive wire. In addition, since the pair of input electrode pins and the pair of input electrode terminals are arranged on a straight line, and the pair of output electrode pins and the pair of output electrode terminals are arranged on a straight line, work efficiency is good. become. In addition, by providing the input and output electrode terminals, the connection bar portions of the input and output electrodes can be formed thin, acoustically reflected waves can be favorably suppressed, and a bonding portion is formed in each connection bar portion. And unnecessary surface acoustic waves are no longer generated from the bolting part.
The frequency characteristics, especially the rising characteristics and the stop band characteristics, are improved. Further, the connecting bar portions of the input and output electrodes and the terminal portions for the input and output electrodes are connected to the connecting bar portions by the connecting bar extensions respectively extending from the connecting bar portions at a predetermined acute angle. Unnecessary surface acoustic waves generated from the bar extension travel at a right angle to the extension and do not go to the output electrode.Therefore, it is possible to eliminate the effects of providing each connecting bar extension and maintain good frequency characteristics. it can.

[0009]

Next, embodiments of the present invention will be described. Also in this embodiment, as shown in FIGS. 1 and 7 to 9, a rectangular piezoelectric substrate 10 is provided on a metal base 20 and an apodized (weighted) electrode And the output electrode 12 formed of a regular electrode are opposed to each other. The input electrode 11 includes a pair of comb-shaped electrodes 11a and 11b.
Reference numerals 1a and 11b denote connecting bar portions 11a2 and 11, respectively, which are parallel and opposed to the side end surfaces 10a and 10b of the piezoelectric substrate 10, respectively.
1b2. The output electrode 12 also includes a pair of comb-like electrodes 12a and 12b, and each of the comb-like electrodes 12a and 12b
Have connecting bar portions 12a2, 12b2 which are parallel and opposed to the side end surfaces 10a, 10b of the piezoelectric substrate 10, respectively. In addition, in FIG. 1, each connection bar part 11a
2, 11b2, 12a2, and 12b2, a plurality of comb teeth portions 11a1, 11b1, and 12a extending at right angles, respectively.
1, 1b1 is omitted. Also, input electrode 1
1 and the output electrode 12 between the conductive wires 17a and 17b.
And a shield electrode 17 connected to the metal base 20 through the shield electrode 17. The shield electrode 17 suppresses propagation of direct waves such as electromagnetic waves and electrostatic induction waves from the input electrode 11 to the output electrode 12.

On the piezoelectric substrate 10, there are formed input electrode terminals 31, 32 having an area necessary for bonding for the connecting bar portions 11a2, 11b2 of the input electrode 11. These input electrode terminal portions 31 and 32 are located outside of the connecting bar portions 11a2 and 11b2, respectively, close to the side end surfaces 10a and 10b of the piezoelectric substrate 10, and perpendicular to the end surfaces 10a and 10b. They are located close and equidistant. Each connecting bar portion 11a2, 11
From the end on the end face 10c side of b2, a pair of connecting bar extensions 33, 34 formed of the same thin strip conductors as the connecting bar portions 11a2, 11b2 at an acute angle toward the input electrode terminal portions 31, 32, respectively. The connecting bar portions 11a2 and 11b2 and the input electrode terminal portions 31 and 32 are extended.
Are electrically connected via connecting bar extensions 33 and 34. The sound absorbing agent 15 is applied to the piezoelectric substrate 10 on the end face 10 c side of the input electrode 11, avoiding the input electrode terminals 31, 32 and from above the connecting bar extensions 33, 34.

Each connecting bar portion 12a2,1 of the output electrode 12
Output electrode terminal portions 35 and 36 having an area necessary for bonding for 2b2 are also formed on the piezoelectric substrate 10. These output electrode terminal portions 35 and 36 are located outside of the connecting bar portions 12a2 and 12b2, respectively, close to the side end surfaces 10a and 10b of the piezoelectric substrate 10, and perpendicular to the end surfaces 10a and 10b. They are located close and equidistant. Each connecting bar portion 12a2, 12b2
From the end on the side of the end face 10d, a pair of connecting bar extensions 37, 38 formed of narrow band-shaped conductors similar to the connecting bar portions 12a2, 12b2 at an acute angle are symmetrical toward the output electrode terminal portions 35, 36, respectively. The connecting bar portions 12a2, 12b2 and the output electrode terminal portions 35, 3
Numeral 6 is electrically connected via connecting bar extensions 37, 38. The sound absorbing agent 16 is applied to the piezoelectric substrate 10 on the end surface 10 d side of the output electrode 12, avoiding the output electrode terminal portions 35 and 36 and from above the connecting bar extension portions 37 and 38.

On the other hand, the lead pin 23 and the ground pin 24 for the input electrode 11 fixed to the metal base 20 are
It protrudes in the vicinity of each side of the piezoelectric substrate 10 and on a straight line connecting the input electrode terminals 31 and 32. Input electrode terminals 31, 32, lead pin 23 and ground pin 2
As shown in FIG. 5, each end is bonded to the input electrode terminal portions 31 and 32 with some slack as shown in FIG. 5 and the other end is formed on the upper surface of the lead pin 23 and the ground pin 24 in order to increase the tensile strength. Are connected to each other by conductive wires 41 and 42 bonded to each other. Also, the lead pin 27 and the ground pin 28 for the output electrode 12 fixed to the metal base 20 protrude to a position on a straight line near each side of the piezoelectric substrate 10 and connecting the output electrode terminals 35 and 36. I have. Output electrode terminal 35,
The lead 36, the lead pin 27 and the ground pin 28 are provided with some slack as shown in FIG. 5 to increase the tensile strength, one end of which is bonded to the output electrode terminal portions 35 and 36, and the other end of which is the lead pin. 27 and the conductive wires 43, 4 bonded to the upper surfaces of the ground pins 28.
4, respectively.

Next, a first modification of the embodiment of FIG. 1 will be described. In this first modification, as shown in FIG.
Although an apodized (weighted) electrode is employed as the input electrode 11, the connecting bar portions 11a2, 11
The distance between b2 is shorter than in the above embodiment, and the length of both connecting bar portions 11a2 and 11b2 is longer than in the above embodiment. Therefore, the input electrode terminal portion 3
Reference numerals 1 and 32 denote the inside of the sound absorbing agent 15 and the piezoelectric substrate 10.
The connecting bar extension portions 33 and 34 are symmetrically extended from the intermediate portions of the connecting bar portions 11a2 and 11b2 to the input electrode terminal portions 31 and 32 at an acute angle. Similarly, in the output electrode 12 formed of the regular electrode, the connection bar portion 12a2,
The distance between 12b2 is shorter than in the above embodiment, and the length of both connecting bar portions 12a2, 12b2 is longer than in the above embodiment. Therefore, the output electrode terminal portions 35 and 36 are located inside the sound absorbing agent 16 and
The connecting bar extension portions 37, 38 are symmetrically extended from the intermediate portions of the connecting bar portions 12a2, 12b2 to the output electrode terminal portions 35, 36 at an acute angle from the intermediate portions of the connecting bar portions 12a2, 12b2. The lead pins 23 and the ground pins 24 are near both sides of the piezoelectric substrate 10 and are on the same straight line as the input electrode terminals 31 and 32, and the conductive wires 41 and 4
2, the lead pins 27 and the ground pins 28 are near both sides of the piezoelectric substrate 10 and are on the same straight line as the output electrode terminals 35 and 36, and
The other points such as the connection by 3 and 44 are the same as the configuration of the above embodiment.

Next, a second modification of the embodiment shown in FIG. 1 will be described. In the second modification, as shown in FIG.
Both the input electrode 11 and the output electrode 12 employ apodized (weighted) electrodes. The input electrode 11 is provided near the side end face 10 b of the piezoelectric substrate 10.
Is provided near the side end face 10 a of the piezoelectric substrate 10. A multistrip coupler (MSC) 18 is provided between the input electrode 11 and the output electrode, so that the surface acoustic wave transmission characteristics are improved. Other points are the same as those in the above embodiment.

Next, a third modification of the embodiment of FIG. 1 will be described. This third modified example, as shown in FIG.
The distance between the connecting bar portions 11a2 and 11b2 of the input electrode 11 is shorter than in the second modification, and the length of both connecting bar portions 11a2 and 11b2 is longer than in the second modification. I have. In addition, the distance between the connection bar portions 12a2 and 12b2 of the output electrode 12 is configured to be shorter than that in the case of the second modification, and both connection bar portions 12a
The length of 2,2b2 is also longer than in the second modification. The connecting bar extension portions 33, 34, 37, 38 are symmetrically extended from the intermediate portions of the connecting bar portions 11a2, 11b2, 12a2, 12b2 at an acute angle, and the input electrode terminal portions 31, 32 and the output electrode terminal portion 35, Other points such as the point guided to 36 are the same as those in the first modification.

In the embodiment and each modified example configured as described above, the input electrode terminal is provided on the piezoelectric substrate 10 outside each of the connecting bar portions 11a2, 11b2, 12a2, 12b2 of the input electrode 11 and the output electrode 12. Portions 31 and 32 and output electrode terminal portions 35 and 36 are provided, respectively.
Each connecting bar portion 11a2, 11b2, 12a2, 12b2
And the respective terminal portions 31, 32, 35, 36 via the respective connecting bar extension portions 33, 34, 37, 38, and the respective terminal portions 31, 32, 35, 36 and the input electrode pins 23, 24.
And the output electrode pins 27 and 28 are connected by the conductive wires 41 to 44, respectively, so that the converter portion including the piezoelectric substrate 10, the input electrode 11, the output electrode 12, and the like of various sizes can have a predetermined size. In this case, the length of the conductive wires 41 to 44 can be reduced to a predetermined short length. Therefore, the wire pulling strength can be increased to prevent wire breakage and wire peeling, frequency characteristics can be prevented from deteriorating due to slackness of the conductive wires 41 to 44, and the production cost can be reduced by reducing the materials of the conductive wires 41 to 44. And workability is improved. In addition, the pair of input electrode pins 23 and 24 and the pair of input electrode terminals 31 and 32 are arranged on a straight line,
Since the pair of output electrode pins 27 and 28 and the pair of output electrode terminals 35 and 36 are arranged in a straight line, work efficiency and productivity are improved.

Further, by providing the input electrode terminals 31, 32 and the output electrode terminals 35, 36, the connecting bar portions 11a2, 11a of the input electrode 11 and the output electrode 12 are provided.
b2, 12a2, and 12b2 can be formed to be thin to suppress acoustically reflected waves satisfactorily, and to provide the connection bar portions 11a
No bonding surface is formed at 2, 11b2, 12a2, and 12b2, and unnecessary surface acoustic waves are no longer generated from the bottoming portion, so that the frequency characteristics, particularly the rising characteristics and the stop band characteristics, are improved. Furthermore, each connecting bar portion 11a2 of the input electrode 11 and the output electrode 12
11b2, 12a2, 12b2 and input electrode terminal 3
1 and 32 and the output electrode terminals 35 and 36 are connected to the respective connecting bar portions 11a2, 11b2, 12a2 and 12b2.
Are connected by the connecting bar extensions 33, 34, 37, and 38, respectively, which extend at a predetermined acute angle, so that the connecting bar extensions 33, 34, 37, and 3 are connected.
Unnecessary surface acoustic waves generated from the extension 8
4, 37, and 38, and does not go to the output electrode 12, so that each connecting bar extension 33, 34, 37, 3
The frequency characteristics can be kept good without the influence of the provision of the reference numeral 8 (see the frequency characteristics in FIG. 6).

Further, in the above embodiment and the second modified example, the sound absorbing agents 15 and 16 are connected to the connecting bar extension portions 33 and 34, respectively.
37, 38, the sound absorbing agent 1
Unnecessary surface acoustic waves due to 5 and 16 can be suppressed better.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state in which a piezoelectric substrate is bonded on a metal base according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a state in which a piezoelectric substrate is bonded on a metal base according to a first modification of the embodiment.

FIG. 3 is a perspective view showing a state in which a piezoelectric substrate is bonded on a metal base according to a second modification of the embodiment.

FIG. 4 is a perspective view showing a state in which a piezoelectric substrate is bonded on a metal base according to a third modification of the embodiment.

FIG. 5 is an enlarged cross-sectional view showing a state in which the input electrode terminal portion and the output electrode terminal portion and each pin according to the embodiment and each modification are connected to respective pins by conductive wires.

FIG. 6 is a frequency characteristic diagram of the embodiment and each of the modifications.

FIG. 7 is a perspective view showing a general example of a surface acoustic wave converter.

FIG. 8 is a partially broken perspective view showing an example of mounting the surface acoustic wave converter.

FIG. 9 is a partially broken perspective view showing another example of mounting the surface acoustic wave converter.

FIG. 10 is a perspective view showing an example of a conventional surface acoustic wave converter.

FIG. 11 is a perspective view showing another example of a conventional surface acoustic wave converter.

FIG. 12 is a perspective view showing another example of a conventional surface acoustic wave converter.

FIG. 13 is a perspective view showing another example of a conventional surface acoustic wave converter.

FIG. 14 is a frequency characteristic diagram of a conventional surface acoustic wave converter.

[Explanation of symbols]

10: piezoelectric substrate, 11: input electrode, 11a, 11b: comb-shaped electrode, 11a1, 11b1: comb-tooth portion, 11a2, 1
1b2: connecting bar portion, 12: output electrode, 12a, 12b
... Comb-shaped electrode, 12a1, 12b1.
2, 12b2 ... connecting bar part, 20 ... metal base, 21,
22, 25, 26 ... conductive wires, 23, 27 ... lead pins, 24, 28 ... ground pins, 31, 32 ... input electrode terminal parts, 33, 34 ... connecting bar extension parts, 35, 36 ... output electrode terminal parts, 37, 38 ... connecting bar extension, 41-
44 ... conductive wire.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-56-37723 (JP, A) JP-A-57-136815 (JP, A) JP-A-63-303506 (JP, A) 67938 (JP, A) JP-A-58-103217 (JP, A) JP-A-60-192524 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H03H9 / 145 H03H9 /twenty five

Claims (1)

(57) [Claims] A rectangular piezoelectric substrate is provided on a metal base, and an input electrode and an output electrode each formed of a pair of comb-shaped electrodes are opposed to each other on the piezoelectric substrate. A pair of input electrodes provided on the metal base and at respective outsides of the side end surfaces of the piezoelectric substrate, each of the connection bar portions of the comb-shaped electrode being provided in parallel with and facing the side end surface of the piezoelectric substrate; Each connecting bar part of the same input electrode is electrically connected to the
Each of the connecting bar portions of the pair of comb-shaped electrodes constituting the output electrode is provided in parallel with and opposed to a side end surface of the piezoelectric substrate, and each of the connection bar portions on the metal base and on each of the side end surfaces of the piezoelectric substrate In a surface acoustic wave conversion device in which each connection bar portion of the output electrode is electrically connected to a pair of output electrode pins provided on the outside, respectively, on the piezoelectric substrate outside each connection bar portion of the input electrode, A pair of input electrode terminals are provided at equal distances from an end surface orthogonal to the side end surface of the piezoelectric substrate, and a predetermined acute angle is formed from each connection bar of the input electrode on the piezoelectric substrate. Each of the input electrode terminal portions and each of the connection bar portions of the input electrode are connected to each other via the extended pair of connection bar extension portions, respectively, on the piezoelectric substrate outside each of the connection bar portions of the output electrode. A pair of output electrode terminals were respectively provided at positions equidistant from an end surface orthogonal to the side end surface of the piezoelectric substrate, and each terminal was extended at a predetermined acute angle from each connection bar portion of the output electrode on the piezoelectric substrate. Each of the output electrode terminal portions and each of the connection bar portions of the same output electrode are connected via a pair of connection bar extension portions, and the pair of input electrode pins and the pair of input electrode terminal portions are aligned. While arranging, each input electrode pin and each input electrode terminal are connected by a conductive wire, respectively, and the pair of output electrode pins and the pair of output electrode terminals are arranged in a straight line, and A surface acoustic wave conversion device, wherein a pin and each output electrode terminal are connected by a conductive wire.