JPH0119460Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to the structure of a mechanical filter.

A mechanical filter uses mechanical resonance, and passes only frequencies near the resonance frequency of a mechanical vibrator, and filters out other frequencies. This means that only when the frequency of the electrical signal matches the resonant frequency of the mechanical resonator, the electrical vibration is converted into mechanical vibration by the transducer on the input side, and then the mechanical vibration is again converted into an electrical signal by the transducer on the output side. It is used to transmit signals.
This has been put into practical use as a low wave number oscillation element or signal selection element. Examples of its applications include telecontrol, pocket bells, answering machines, and recently, it has been put to practical use as a selection element for automatic switching signals for stereo and bilingual television multiplexed audio broadcasts.

Conventionally, mechanical filters have been constructed as shown in FIG. A piezoelectric electro-mechanical conversion transducer 2 is bonded to the tuning fork resonator 1 so as to face each other, and the tuning fork resonator 1 with the transducer 2 attached is spot welded to a support member 3. The support member 3 is supported and fixed to the terminal board 6 by soldering or the like at the ground terminal 4a. Terminal board 6
There are other things in there. Since the structure is such that the lead wire 7 is connected to the transducer 2 provided with the output terminals 4b and 4c, the stress of the lead wire affects the resonant frequency. Frequency adjustment is performed to make this mechanical filter the desired frequency passing filter, and the frequency of a tuning fork is generally expressed by the following equation. When increasing the resonance frequency of the tuning fork by ∞t/l ₂ (here, the resonance frequency of the tuning fork, t is the thickness of the tuning fork, and l is the length of the tuning fork), the length of the tuning fork is shortened. As shown in FIG. 2, the tip 7 of the terminal board 6 becomes distorted during adjustment, making it difficult to sharpen the tip of the tuning fork.

The purpose of this invention is to make it easier to shave the tip of the tuning fork by dividing the terminal board into a small board with terminals (first board) and another board (second board). It is.

Embodiments of the present invention will be described below with reference to FIGS. 3 to 7. FIG. 3 shows the first board of one half of the divided terminal board of the present invention, and FIG. 4 shows the second board of the other half. Reference numeral 13 denotes a first substrate made of plastic or the like, which has a convex protrusion, and is fitted into a recessed portion of the second substrate 17 shown in FIG. On this first substrate 13, 14a and 14b are continuous circles or square bars as conductive terminals, 14c and 14d are also continuous circles or square bars, and 15 and 15a are 1 The part of the book stick indicated by 15 is bent.

The three bars above serve as conductor terminals that transmit electricity.
It is fixed to the board through the board. FIG. 5 is a perspective view showing a state in which each component of the mechanical filter is fixed to the divided first board of FIG. A transducer 23 made of ceramic or the like having a piezoelectric effect is attached to the tuning fork 18. The structure is such that the transducer 23 is electrically connected to terminals by lead wires 19a and 19b, respectively, and signals can be taken out to the outside through conductive terminals 14a to 14d. In the shape of the present invention, unlike the conventional one, the length of the divided first substrate is as short as about half the total length of the tuning fork.

FIG. 7 is a perspective view showing a state in which the convex portion of FIG. 5 and the recessed portion shown in FIG. 4 are fitted together to form an integrated terminal board. Although details are omitted in FIG. 7, the components shown in FIG. 5 are actually fixed to the base body shown in FIG. 3.

That is, the vibrator 18 to which the piezoelectric transducer 23 is fixed is electrically connected to the outside via the conductive terminals 14a to 14d and supported by the lead wires 19a and 19b. These conductive terminals 14a to 14d and support terminal 1
5 penetrates and is fixed to the first substrate 13.
Therefore, in this state, as shown in FIG. 5, the convex portion of the first substrate 13 on which each member is fixed is fitted into the recessed portion of the second substrate 17 shown in FIG. As shown in the figure, it forms one terminal board. Naturally, the relationship between the concave and convex portions may be reversed.

One of the features of the present invention, as shown in Figure 5, is that
The first substrate 13 is shorter than the length of the vibrator 18, that is, the end of the vibrator protrudes from the end of the first substrate 13. The second feature is that the lead wires 19a and 19b have one end connected to the transducer 23 and the other end connected to the conductive terminals 14a and 14c. , 19b have not changed in any way, so in FIG. 7 they are the same as the conventional shape in FIG. 1, that is, the total length of the terminal board is longer than the total length of the tuning fork 18,
Although not shown, the tuning fork 18 enclosed in the case is not in contact and its function as a mechanical filter remains unchanged.

FIG. 6 is a diagram showing the state when frequency adjustment is performed. Reference numeral 24 denotes a grindstone of a grinder, and the tuning fork 18 is held by a holder 21 made of rubber or the like by being movable in a direction 22 of movement thereof. In this state, the grinding wheel 24 of the grinder moves in the direction in which the tip of the tuning fork 18 comes into contact with the grinder, thereby scraping off the tip of the tuning fork and making it possible to adjust the frequency. The adjusted frequency will not change after that.

As described above, according to the present invention, since the first substrate is short when cutting a tuning fork, it is now possible to process items that could not be processed using conventional methods, using an automatic adjustment device that does not require input. At the same time, a mechanical filter with stable frequency accuracy can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a conventional embodiment, FIG. 2 is a diagram for explaining the frequency adjustment state of the conventional embodiment, and FIG. 3 is a perspective view showing the first board of the embodiment of the present invention. 4 is a perspective view showing a second substrate used in combination with FIG. 3 of the embodiment of the present invention,
Fig. 5 is a diagram showing a state in which the lead wire and tuning fork are assembled on the first board of the present invention, Fig. 6 is a side view for explaining the frequency adjustment state of the embodiment of the present invention, and Fig. 7 is a FIG. 3 is a perspective view showing a fitted state of the terminal board according to the embodiment of the present invention. 13...first substrate, 14a, 14b, 14
c, 14d... conductive terminal, 17... second substrate,
18... Tuning fork, 19a, 19b... Lead wire.

Claims (1)

[Scope of utility model registration request] A tuning fork to which a piezoelectric transducer is fixed, and a lead wire, one end of which is connected to the transducer and the other end connected to a plurality of conductive terminals led out to the outside, and the conductive terminals are inserted through the tuning fork. In a terminal board configured of a fixed first board and a second board separate from the first board, the terminal board is comprised of the first board and the second board fitted thereto. . A mechanical filter, wherein a length of the first board parallel to the tuning fork is shorter than the tuning fork, and the fitted terminal board is longer than the tuning fork.