JPH03217110A - Composite longitudinal vibration mechanical filter - Google Patents

Abstract

PURPOSE:To easily constitute a small-sized, light, and thin composite longitudinal vibration mechanical filter of high reliability by sticking supporting members supporting plural longitudinal vibration acoustic pieces and a lead line between a pair of holding members consisting of a cover and a frame. CONSTITUTION:End parts of supporting members 40 and 42 are interposed between holding members 50a and 50b consisting of the cover and the frame and are stuck with a sealing material like epoxy resin. With respect to a composite longitudinal vibration mechanical filter 30 formed in this manner, input- side and output-side longitudinal vibration acoustic pieces 32 and 34 are held without coming into contact with the cover or the like by supporting members 40 and 42, holding members 50a and 50b, and the lead line, and members to determine the performance of this mechanical filter are sealed with holding members 50a and 50b and the sealing material, and input/output can be taken out by a feed line 52, a ground line 52e, a lead-out line 54, and a ground line 54e, and these lines can be directly soldered as electric terminals of the composite longitudinal vibration mechanical filter to a PC board or the like.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a composite longitudinal vibration mechanical filter, and more specifically includes a longitudinal vibrating body (hereinafter referred to as a longitudinal vibrating resonator), a piezoelectric member, a coupling member, a support member, In a composite longitudinal vibration mechanical filter consisting of a structure such as a holding member, the holding member is one
It consists of a set of lids and frames, and by fixing this set of holding members so as to sandwich the support member and leader line, it is possible to easily hold a plurality of vertically vibrating sound bars without contacting the lid etc.
This invention relates to a composite longitudinal vibration mechanical filter that eliminates the need to separately attach electrical terminals.

(Background of the Invention) Recently, mechanical filters have been adopted in communication equipment and the like as an intermediate in terms of characteristics between LC filters and crystal filters. This means that mechanical filters have a good Q
This is because it has good selection characteristics based on the value of , has excellent stability against temperature changes, and can be miniaturized.

An example of this type of composite longitudinal vibration mechanical filter is shown in the third example.
As shown in the figure. As shown in the figure, the composite longitudinal vibration mechanical filter has an input side longitudinal vibration sound piece 2 and an output side vertical vibration sound piece 4, which are arranged on the same plane and made of a metal material or the like. The input longitudinal vibrating sound bar 2 and the output longitudinal vibrating sound bar 4 are integrally formed by constant elastic coupling members 6 and 8. In this case, support members 10 and 12 are provided in a protruding manner at the outer central portions of the input side vertically vibrating sound piece 2 and the output side vertically vibrating sound piece 4. A pair of input side piezoelectric ceramics 14a and 14b are superimposed and fixed to the input side longitudinal vibrating sound bar 2 using soldering or the like.

The ends of the supporting members 10 and 12 are firmly fixed to the upper center of the upright pieces 24a and 24b of the holding member 24 by laser welding or the like. Then, the piezoelectric ceramics 14 on the input side of the composite longitudinal vibration mechanical filter configured in this way
A, 14b and the upright piece 24a are connected with a power supply line 18 for supplying an input signal and a grounding line 18e, and on the other hand, a lead-out line 20 for deriving an output signal and a grounding line 20e are connected. .

Due to the above-described configuration, the input side longitudinal vibration sound piece 2 and the output side vertical vibration sound piece 4, which are connected together by the coupling members 6 and 8, are arranged substantially in the air, so that their longitudinal vibration and other operations are not hindered. Not formed. After the composite longitudinal vibration mechanical filter is housed in a case (not shown), it is attached to an intermediate frequency amplification section of communication equipment, etc., to achieve its desired purpose.

In the composite longitudinal vibration mechanical filter configured as described above, a signal Os
A high-frequency signal S, which has passed through a resistor R, is applied to electrodes (not shown) mounted on the input-side piezoelectric ceramics 14a and 14b, and the high-frequency signal S, which has passed through the resistor R, is applied to the electrodes (not shown) attached to the input-side piezoelectric ceramics 14a and 14b, and the high-frequency signal S is applied to the input-side longitudinal vibrating sound piece 2, which is electrically grounded. Generates a corresponding electric field. Due to this electric field, the input side piezoelectric ceramics 14a and 14b generate electrostriction in the directions shown by Vm and Vn in the figure, and the frequency F1 is set so that the length L1 of the input side longitudinal vibrating bar 2 is a half wavelength of the longitudinal wave.
resonates with If the average propagation velocity of the longitudinal wave in the input side longitudinally vibrating acoustic bar 2 is V, the frequency F1 is given by the following equation.

F1=V/(2L1)・
... (1) This longitudinal vibration at frequency F1 is mechanically coupled to the output side longitudinal vibration sound bar 4 at the coupling members 6 and 8, and the output side longitudinal vibration sound bar 4 produces longitudinal vibration at frequency F2 due to the length L2. resonates with Similar to equation (1), this frequency F2 is calculated as follows, assuming that the average propagation velocity of the longitudinal wave of the output longitudinally vibrating sound piece 4 is V, then F2=V/ (2 L2) ... (2)
becomes. The voltage generated in the output piezoelectric ceramics 16a and 16b due to the longitudinal vibration of the output longitudinally vibrating sound piece 4 is a high frequency signal S2 formed into a predetermined, for example, steep frequency characteristic between the lead wire 20 and the ground wire 2Oe. It can be derived as

By the way, this type of filter has strict performance standards and must maintain its characteristics even under harsh environmental conditions, so the housing that houses this complex longitudinal vibration mechanical filter is a large metal-sealed bag cage. , and are expensive, hindering miniaturization, thinning, and cost reduction of devices.

(Object of the Invention) The present invention has been made to overcome the above-mentioned disadvantages, and has a support member for supporting a plurality of vertically vibrating acoustic bars and a leader line by a holding member consisting of a lid and a frame. The purpose of the present invention is to provide an inexpensive, small, lightweight, and thin composite longitudinal vibration mechanical filter that is fixed in a sandwiching manner and configured such that the leader wire is drawn out to the outside of the holding member to a required length.

(Means for Achieving the Object) In order to achieve the above object, the present invention provides a composite longitudinal vibration mechanical filter that forms and derives a supplied high frequency signal into a predetermined frequency band. a plurality of vibrating bodies including an output side, a piezoelectric member having an electrode plate superimposed on the input side vibrating body and the output side vibrating body for connecting a conductor, and a plurality of piezoelectric members that connect between the plurality of vibrating bodies. a coupling member, a supporting member formed protruding from the input-side vibrating body and the output-side vibrating body, and the supporting member is attached to hold a plurality of vibrating bodies including the input-side and output-side vibrators. The structure includes a holding member and a leader line for inputting or outputting a high frequency signal to the electrode plate of the piezoelectric body, and the holding member is composed of a set of a lid and a frame, and the set of holding member is composed of a lid and a frame. The support member and the lead wire are sandwiched and fixed to hold the plurality of vibrating bodies without contacting the lid or the like, and the power supply line is drawn out to the outside of the holding member for a necessary length so that it also serves as an electric terminal.

(Embodiment) Next, a preferred embodiment of the composite longitudinal vibration mechanical filter according to the present invention will be described in detail with reference to FIG. 1.

In FIG. 1, reference numeral 30 indicates an embodiment of the composite longitudinal vibration mechanical filter according to the present invention, and the composite longitudinal vibration mechanical filter 30 includes an input longitudinal vibration acoustic bar 32 and an input longitudinal vibration acoustic bar 32. It has an output-side longitudinal vibrating sound piece 34 of the same shape.

Connecting members 36 and 38 made of thin constant elastic material are formed between them. Further, the input side tII vibrating sound piece 32 and the output side vibrating sound piece 34 are provided with support members 40 and 42 protruding from their central portions.

A pair of input-side piezoelectric ceramics 44a and 44b are superimposed and fixed to the input-side longitudinal vibrating sound piece 32 by soldering or the like. Similarly, output side piezoelectric ceramics 46a and 46b are superimposed and fixed on the output side longitudinally vibrating sound piece 34 as well. Input side piezoelectric ceramics 44a, 44b and output side piezoelectric ceramics 46a. Electrodes (not shown) such as metallization have been formed in advance on the surface of each of the electrodes 46b. The ends of the supporting members 40 and 42 are sandwiched between holding members 50a and 50b, each consisting of a lid and a frame, and fixed with a sealing material such as epoxy resin. Furthermore, input side and output side piezoelectric ceramics 44a. A feed line 52 and an output line 5 for feeding and deriving high frequency signals to 44b, 46a, and 46b.
4 is wired, and ground wires 52e and 54e are wired, and these lead wires are connected to the holding member 50a. 50b
It is sandwiched and fixed.

The mechanical filter 30 of the present invention is constructed as described above, and the operation thereof and the effects of this embodiment will be explained next.

First, a pair of input side piezoelectric ceramics 44a and 44b
A high frequency signal S4 is generated from a signal source Osc via a resistor R via a feeder line 52 and a ground line 52e between the input side vertically vibrating acoustic bar 32 and a frequency converter such as a super heterodyne receiver. An intermediate frequency signal of 455KH↓ is supplied.

As a result, the input side vertical vibration sound bar 3 electrically grounded
2, an electric field corresponding to the high frequency signal S4 is generated through input side piezoelectric ceramics 44a and 44b. Due to this electric field, the input side piezoelectric ceramics 44a and 44b produce electrostriction in the directions shown by arrows mi and mO in the figure, and the input side longitudinal vibrating resonator 32 resonates at a frequency F4 where the length L4 is a half wavelength of the longitudinal wave. do. Assuming that V is the average propagation velocity of the longitudinal wave in the input-side constricted vibration acoustic bar 32, the frequency F4 is given by the following equation.

F4=V/ (2L4) ... (3)
This longitudinal vibration is mechanically coupled and propagated to the output side vertical vibration sound piece 34 via the coupling members 36 and 38, and the output side longitudinal vibration sound piece 34 responds with a vibration of frequency F5 due to the length L5,
In other words, it resonates with longitudinal vibration.

This frequency F5 is determined by the output side longitudinal vibrating sound piece 3 as in equation (3).
If the average propagation velocity of longitudinal waves of 4 is V, then F 5=
V/ (2 L5) ... (4). Due to the electrostriction of the longitudinal vibration of the output longitudinal vibration vibrating bar 34, a voltage is generated in the electrodes (not shown) of the output side piezoelectric ceramics 46a and 46b, and a predetermined steep frequency characteristic formed due to the propagation of the longitudinal vibration, etc. , an intermediate frequency signal of, for example, 455 KHz formed into a narrow band frequency characteristic is derived as an output signal S5 from the output line 54 and the ground line 54e.

In the composite longitudinal vibration mechanical filter 30 formed in this way, the input side and output side longitudinal vibration acoustic bars 32.
34 is a holding member 50a. 50b and a leader line,
In addition, while the members that determine the performance of these composite longitudinal vibration mechanical filters are sealed with the holding members 50a and 50b and the sealing material, the input and output are connected to the power supply line 52, the grounding line 52e, the lead-out line 54, and the grounding line 54e. These conductive wires can also be directly soldered to a PC board or the like as electrical terminals of the composite longitudinal vibration mechanical filter.

(Effects of the Invention) As explained above, by sandwiching and fixing the supporting member that supports a plurality of longitudinal vibration acoustic bars and the leader wire between a pair of holding members consisting of a lid and a frame, the device can be made compact, lightweight, and thin. This has the effect of easily constructing a highly reliable composite longitudinal vibration mechanical filter.

The above explanation is for a structure with only input and output sound pieces, but the same effect can be obtained in a case where there are a plurality of longitudinal vibration sound pieces between input and output sound pieces as shown in Fig. 2. Of course.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an example of a composite longitudinal vibration mechanical filter according to the present invention, and FIG. 2 is a perspective view of another example of the present invention.
FIG. 3 is a perspective view showing the structure of a conventional composite longitudinal vibration mechanical filter. 32... Input side vertical vibration sound piece, 34... Output side vertical vibration sound piece, 36.38... Coupling member, 40.42... Support member, 44a. 44b... Input side piezoelectric ceramics, 46a+ 46b... Output side piezoelectric ceramics, 5
0a, 50b... Holding member, 52... Power supply line, 52
e, 54e...ground wire, 54...output line.

Claims (1)

[Claims] A composite longitudinal vibration mechanical filter that forms and derives a supplied high-frequency signal into a predetermined frequency band includes a plurality of vibrating bodies including an input side and an output side of the high-frequency signal, and the input side vibrating body and the output side vibrating body. a piezoelectric member having electrode plates for connecting conductors superimposed on each other; a plurality of coupling members connecting the plurality of vibrating bodies; and a piezoelectric member provided protruding from the input side vibrating body and the output side vibrating body. a support member formed of a support member; a holding member to which the support member is attached to hold a plurality of vibrating bodies including the input side and the output side; and a support member for inputting or outputting a high frequency signal to the electrode plate of the piezoelectric body. The holding member is composed of a set of a lid and a frame, and this set of holding members sandwiches and fixes the supporting member and the lead wire, so that the plurality of A composite longitudinal vibration mechanical filter characterized by holding a vibrating body without contacting a holding member.