JPS60142699A - Dynamic receiver - Google Patents

Abstract

PURPOSE:To obtain a dynamic receiver whose sound pressure in low band frequency is sufficiency attenuated, by providing an acoustic tube which leads into a front air chamber the high pressure generated in a back air chamber between the back air chamber and the front air chamber partitioned by a diaphragm. CONSTITUTION:A magnetic pole circle plate 20, magnet 21, yoke 22 are respectively connected in concentric circles, thus producing a magnetic circuit. A voice coil 24 is connected to a diaphragm 23 and inserted into a clearance comprising the plate 20 and the yoke 22. The diaphragm 23 is connected to a case 25 and mounted on an outer case 26. In the case 26, a front air chamber 29, back air chamber 30 and inner air chamber 31 are formed, and the chamber 29 and the chamber 30 are acoustically connected by an acoustic tube 33, by which attenuation of the low band output acoustic pressure allows good frequency characteristics without a thick diaphragm.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a dynamic receiver used in a telephone receiver or the like.

Conventional configuration and its problems FIG. 1 shows a conventional dynamic receiver.

The configuration of this conventional example will be explained below with reference to FIG.

In FIG. 1, 1 is a magnetic pole disk, 2 is a magnet, and 3 is a yoke, each of which is connected on a concentric circle fL to form a magnetic circuit. 6 is a voice coil 2 connected to a diaphragm 4 having a small hole 13 in its center;
The voice coil 6 is inserted into a gap formed between the magnetic pole disk 1 and the yoke 3, and the diaphragm 4 is coupled to the case 6. 7 is an outer case, which is connected to the case 6.

8 is an equalizer kissep having an opening 8', and is connected to the outer case 7. 9 is an acoustic resistance material, 1
o is a front air chamber, 11 is a back air chamber, and 12 is an internal air chamber.

Next, the operation of the above conventional example will be explained. FIG. 2 shows a conventional equivalent circuit. Here, r□, m□-〇 are the impedances of the diaphragm 4, Sl is the steno stiffness of the internal air chamber 12, resistance of the acoustic resistance material 9 of R1, Sb is the steno stiffness of the back air chamber 11, and R2:M2 is the imaging 1fi4 resistance and equivalent mass of the pore 13, Sh is the stem funness of the front air chamber 1o, Mh is the equivalent mass of the opening 8' of the equalizer cab,
So is the stiffness of a coupler (not shown) used in measuring the characteristics, P is the output sound pressure, and S is the diaphragm surface.

3-.

In this Vane circuit, the elements that can control all the low frequency characteristics are the impedance AO of the diaphragm 4 + the equal image mass of the pore 13 of the imaging plate 4 and the resistance M2°R2. By the way, in order to eliminate noise generated on the telephone line and in the surrounding environment of the caller, it is necessary to completely attenuate the output sound pressure of 300 Hz or less in the frequency characteristics of the receiver.
It is said that the higher this value is, the better the clarity of calls will be.

In the conventional example, in order to completely attenuate the output level below 3 ooHz, the noise waveform is made thicker and the impedance/6° is increased.

However, in this case, in the conventional example, 10
It uses a thermoformed plastic film with a thickness of approximately 0μ, and therefore has poor moldability and poor precision, so there is a problem that it is limited to simple shapes.
Ta.

Purpose of the Invention The present invention eliminates the problems of the conventional example described above, and provides an excellent fL2 dynamic type that can sufficiently attenuate sound pressure at low frequencies with a simple configuration without increasing the thickness of the imaging plate. The purpose is to provide a receiver.

Structure of the Invention In order to achieve the above-mentioned object, the present invention is designed to detect a sound that is separated by a photographing plate between the back air chamber and the front air chamber, which is 180 degrees out of phase with the high pressure of the front air chamber generated in the back air chamber. An acoustic tube is installed that guides the pressure to the front air chamber and cancels it out.

This fLK is used to attenuate the low frequency output sound pressure.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 3, 20 is a magnetic pole disk, 21 is a magnet, and 22
are yokes, each of which is connected on a central circle to form a magnetic circuit. Reference numeral 24 denotes a voice coil, which is coupled to an imaging plate 23 having a pore 32 in its center.The voice coil 24 is inserted into a gap formed by the magnetic pole disk 20 and the yoke 22, and is connected to the imaging plate 23. 23 is coupled to a case 26. 26 is an outer case and is combined with the case 26, and 27 is an equalizer 6 page cap having an opening 27' and is combined with the outer case 2e.

2 is an acoustic resistance material, 29 is a front air chamber, 3° is a back air chamber, 31 is an internal air chamber, and 331d is an acoustic tube. are combined.

Next, the operation of the above embodiment will be explained. FIG. 4 shows the equivalent circuit of the above embodiment. Here, rO11f! i23
S71 is the stiffness of the front air chamber 29, and Mfi is the equalizer cap 27.
The isometric mass of the aperture 27', SO is the stiffness of a Kerr J bra (not shown) for measurement. R3 and M3 are the resistance and isometric mass of the acoustic tube 23. Also 1) l-1t
Output sound pressure, P is the sound pressure in the back air chamber, R2 is the sound pressure in the front air chamber, S is the diaphragm area, i is the input current, E is the input voltage, and M1 is the force coefficient.

In this circuit, in the low frequency range, the sound 6 page pressure P1 having a 180° phase difference with the high pressure P2 generated by the back air chamber 301 is guided to the front air chamber 29 through the acoustic tube 331 &: and the front air chamber 29. Although it is synthesized with the sound pressure P2, since the phase is opposite, it is canceled out, and the output sound pressure P is attenuated. As the frequency moves to a higher range, the impedance of the acoustic tube 33 (Ra
Since ωM3) increases, the sound pressure in the back air chamber 3o becomes irrelevant to the output sound pressure.

In this embodiment, the impedance Ao of the imaging plate 23 is
2. Since the low-frequency output sound pressure can be attenuated without increasing the value, good frequency characteristics can be obtained without using a thick imaging plate. Therefore, a plastic film with a thickness of 30 to 40 μm can be used for the photographing plate 23vc, which facilitates the molding process, and furthermore, even if the plate has a complicated shape, it is extremely easy to process it. FIG. 6 shows the frequency characteristics of the dynamic receiver according to this embodiment. From this figure, it can be seen that according to this embodiment, the output sound pressure at low frequencies is significantly attenuated.

Effect of the invention As is clear from the above embodiments, the present invention has a front surface 7.

11-n An acoustic tube is installed between the air chamber and the back air chamber.

The following effects can be obtained.

(1) Since the imaging plate can be made thinner, the molding process of the plastic film becomes much easier.

(2) The shape of the perturbation plate is not limited to a simple one, and the entire receiver can be configured to have an arbitrarily complex shape.

[Brief explanation of drawings]

Figure 1 is a sectional view of a conventional dynamic receiver, Figure 2 is a cross-sectional view of a conventional dynamic receiver.
The figure is an equivalent circuit diagram of a conventional dynamic type receiver, and FIG. 3 is an output sound pressure frequency characteristic diagram of a dynamic type receiver according to an embodiment of the present invention. 23...Vibration resistance, 24...Voice coil, 25...Case, 29...Front air chamber, 30...Back air chamber . , name of agent Patent attorney Toshio Nakao and one other person Figure 1 Figure 2 Figure 3 Page 4 Page 5

Claims (1)

[Claims] A diaphragm, a case for fixing the diaphragm, and a front air chamber and a back air chamber formed by the diaphragm and the case, and for guiding all the high pressure generated in the back air chamber to the front air chamber. A dynamic receiver characterized by being equipped with an acoustic tube.