DE1250568A1 - - Google Patents

Description

UNDESREPUBLIK DEUTSCHLAjH ^

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl.

H 03 h

German class: 21 g - 34

Number: 1 250 568

File number: T 12835 IX d / 21 g
Filing date: November 5, 1956

Opening day: September 21, 1967

The invention relates to a mechanical frequency filter in which several resonance bodies of the same type as well as one or more coupling lines each connecting all the resonance bodies to one another made of homogeneous wires are provided and in which the sound box, for which Due to their structure, line sections with uniform inductance and capacitance as electrical ones Equivalent circuit result, have different coupling factors.

There are now different ways, a different coupling factor between the resonance bodies of a mechanical frequency filter.

For example, it is known that the. Coupling factors due to different dimensions adjust the coupling elements. It should be noted, however, that when too longitudinal Vibrations excited resonance bodies, the coupling factor is equal to the square of the diameter of the coupling wire changes, so that only a limited range of degrees of coupling with mechanical still to be realized diameters of the coupling wires can be obtained.

A mechanical filter is also known from US Pat. No. 2,518,452, in which the resonance body and coupling elements alternately follow one another along a common axis, the different coupling between the resonance bodies is achieved in that the coupling elements at the bottom of holes made in the sound box in the direction of the longitudinal axis attack. This known mechanical frequency filter has the disadvantage that there are great difficulties prepares to fix the coupling elements at the bottom of the holes so that a perfect Coupling results. Another way to achieve different couplings is to use the To attack coupling elements at different points of the resonance body.

Such a filter in which disc-shaped resonators are eccentrically attached coupling elements interconnected is known from U.S. Patent 2,615,981.

U.S. Patent 2,753,524 describes a mechanical filter assembly in which use is also made of the fact that the coupling factor depends on the position of the Attachment points "of the coupling elements on the resonators is dependent in such a way that the Coupling becomes greater the closer the attachment point is to the end of a resonator.

It has already been proposed (German patent mechanical frequency filter

Applicant:
Telefunken

Patentverwertungsgesellschaft mb H.,
Ulm / Danube, Elisabethenstr. 3

Named as inventor:

Dipl.-Phys. Dr. rer. nat. Manfred Börner,

Ulm / Danube

writing 1 133 047), in the case of mechanical frequency filters, consisting of several transistor oscillations excitable resonance bodies arranged axially parallel, for coupling the individual resonance bodies with prescribed different degrees of coupling, the continuous to longitudinal vibrations excitable coupling elements at points of different oscillation amplitudes of the jacket or To attack the end faces of preceding and / or following resonance bodies.

A frequency filter according to the invention is characterized by resonance bodies of such a shape, with such a vibration mode and in such a spatial arrangement within the filter vibration system, that the coupling lines on surface points of the resonance bodies are selected according to the amplitude of movement of these surface points Distances from the resonator node level can be attached, which the desired coupling factors result between adjacent resonance bodies; mechanical frequency filters are excluded, the axially parallel to each other arranged from several excitable to torsional vibrations Resonance bodies and consist of at least one coupling line, which longitudinal vibrations executes.

To explain the invention in more detail, it will be described in more detail using an exemplary embodiment. 1 shows a four-circle filter with resonance bodies 1, 2, 3 and 4 excited in longitudinal vibrations, which are coupled to one another by two wires 7 and 8 of constant cross section stretched between fixed planes 5 and 6. When the fundamental waves of the individual resonance bodies are excited in longkydinal oscillations, the ends of the individual cylinders carry out the greatest amplitude of movement, while the amplitude of movement decreases towards the center of each resonance body. To achieve different coupling

709 648/278

Claims (2)

According to the invention, the connection points of the coupling wires 7 and 8 with the resonance bodies are selected differently to achieve degrees of efficiency of the individual resonance bodies. In the case of the bodies 1 and 2, the connections with the coupling wires 7 and 8 are e.g. B. carried out by welding at the ends of the cylinders at points 11, 12, 13, 14 and 21, 22, 23, 24, respectively. In the case of bodies 3 and 4, the connection points are closer to the center at points 31, 32, 33, 34 and 41, 42, 43, 44, respectively, so that these bodies are more weakly coupled to the coupling wires 7 and 8 than the previous ones. If one denotes the distances between the attachment points on the individual vibrating bodies a 1, 2, 3 and 4 with L1, L2, L3, L4 and the total length of each vibrator with L, then the following applies to the coupling factor between two consecutive bodies i and k (i, k = 1, 2, 3, 4) the equation sin 2 ^ -1 (1) Here, K0 is the maximum achievable coupling factor in the event that the coupling wires are welded to the ends of the cylinders. This coupling factor is essentially dependent on the diameter ratio of the vibrating body and the coupling wires as well as on the materials. The filter can e.g. B., as indicated in the drawing, are coupled by electromechanical converters 9 and 10 to the external electrical circuits. ίο The embodiment according to F i g. 1 shows an arrangement with two coupling wires which are each fastened symmetrically to the vibration nodes on each vibrating body. However, the invention can also be used with any other number of coupling wires. It is also not necessary for the attachment to take place symmetrically on the oscillating bodies. If any number η of coupling wires is used, which are attached to the individual vibrating bodies at different distances from the vibration node, then the following applies for the coupling factor Kik of two consecutive vibrating bodies, which should be marked with the index i or k: sin -y sin - - 2 ^ -1 where the index / denotes the relevant coupling wire. For a filter with two coupling wires, an embodiment of such a general coupling type is shown in FIG. 2 reproduced. In contrast to FIG. i the coupling wires 7 and 8 attached to each oscillating body at different distances from the vibration node, the index i denoting the oscillating body and the index / the relevant coupling wire. For this special embodiment, the formula (2) is in the following form: Kik = K0 sin π / - Lk2 Sin 2 2 L ■ (3) Here, K0 is the maximum coupling factor that can be achieved with a single coupling wire. Patent claims: 1.Mechanical frequency filter, in which several resonance bodies of the same type and one or more coupling lines made of homogeneous wires, each connecting all the resonance bodies to one another, are provided and in which the resonance bodies, for which, due to their structure, line pieces with uniform inductance and capacitance are obtained as an electrical equivalent circuit diagram, have different coupling factors, characterized by resonance bodies (1 to 4) of such shape, with such a vibration mode and in such a spatial arrangement within the filter vibration system that the coupling lines (7, 8) on surface points (e.g. 11 to 14; 12 to 24 ) the resonance bodies can be fastened at distances from the resonator node plane selected according to the amplitude of movement of these surface points, which give the desired coupling factors between adjacent resonance bodies; Exceptions are mechanical frequency filters, which are made up of several axis- For this purpose 1 sheet of S resonance bodies arranged parallel to one another and consisting of at least one coupling line, which performs longitudinal vibrations. 2. Mechanical frequency filter according to claim 1 with a plurality of resonance bodies arranged one behind the other in the same axis, excited in longitudinal vibrations, characterized in that at least two axially parallel coupling wires (7, 8) are provided which are symmetrical to the center of vibration of each resonance body at points (z. B. 31 to 34; 41 to 44) are fastened between the center of oscillation and the base and top surfaces on the relevant resonance bodies (e.g. 3 to 4), in particular by welding. Considered publications:
French Patent No. 1,018,542;
U.S. Patent Nos. 2,578,452, 2,615,981, 652,543, 2,753,524. Legacy Patents Considered:
German Patent No. 1133 047. 709 648/278 9.67 © Bundesdruckerei Berlin