SU50775A1 - Electrodynamic narrowband microphone - Google Patents

Description

As is well known, a mechanical acoustic system of an electrodynamic microphone can be represented by an electrical equivalent circuit.

In the manufacture of a microphone-acoustic system, the implementation of the characteristic impedance, to which such a circuit is closed, causes particular difficulties. Most often it is performed in the form of slits and gates, the width of which is very small and which, therefore, has to be done scientifically.

Meanwhile, if the microphone is calculated over a narrow frequency range, the thickness of such a slit may have a size close to that of the gap between the moving coil / and pole piece 2 (Fig. 1), but the depth of the slit is usually determined by magnetic and electrical considerations and therefore may not coincide with the required, based on the required mechanical resistance.

As a result, the mechanical backlash resistance can be either less or more than desired.

If it is mechanical

if the resistance is small, then according to the invention, it can be increased by increasing the length of the frame on which the moving coil is wound, beyond the limits required for winding, so that the air has to travel a longer way.

The second wall of the gap (the first wall-inner side of the frame) can be done either by increasing the thickness (height) of the pole piece, or, if undesirable, based on magnetic conditions, by means of a ring 5 of non-magnetic material worn under the pole piece 2 on the core 4 (FIG. . one).

If, on the contrary, the resulting mechanical resistance is large, it can be shunted by a second backlash, located between the outer side of the moving coil and the flange of the magnetic circuit. This shunting is carried out through holes 6 (Fig. 2) located in the upper part of the frame of the movable roller (along its circumference).

The air here has the opportunity to pass not only through the internal play, but also through the external due to the holes 6. The flow paths

air in this case is shown in FIG. 2 arrows.

Of course, if necessary, it is possible not only to shunt one gap with another, but also to increase the length of the air paths by increasing the height of the frame and increasing the thickness of the pole piece and flange or by imposing non-magnetic rings under the pole piece.

Thus, by combining all the above-mentioned methods, it is possible to achieve the desired value of mechanical resistance.

Made according to the invention, the sample gave a positive result. Such a narrowband electrodynamic microphone design provides uniform frequency response without any auxiliary details.

The subject matter of the invention.

Claims (3)

1. Electrodynamic narrowband microphone, characterized in that, in order to obtain a mechanical frequency response that provides a uniform frequency response by using a backlash between the inner surface of the moving coil frame and the pole piece, the frame of the moving coil is extended beyond the limits required for winding, and the pole piece corresponds to this extension A core of a nonmagnetic material is placed on the core or under it. 2.Varification of the microphone according to claim 1, characterized in that to obtain a lower mechanical resistance, the backlash between the inner side of the frame of the moving coil and the pole piece is shunted by the gap between the flange of the magnetic circuit and the outer side of the frame of the moving coil through holes in the upper part of the frame of the moving coil connecting both of these backlash. 3. The form of the microphone but clause 2, characterized in that to increase the resistance of the shunt P1, its backlash the thickness of the magnetic circuit flange is increased or under the latter a ring of non-magnetic material is fixed. Lig.2