JPH05207582A - Directive dynamic microphone unit - Google Patents

Abstract

PURPOSE:To easily realize the directive dynamic microphone unit having a performance whose output frequency characteristic is revised. CONSTITUTION:Plural ring projections 15 having a different inner diameter are provided around a rear sound hole 14 provided on part of a bottom face of a synthetic resin case 8 to which an inner air chamber 9 and a phase shift circuit sound terminal 10 together with an acoustic yoke 7 are provided. The rear acoustic resistive member 16 is placed on the ring projection 15 and a ring projection 15 whose characteristic is in matching with a desired output frequency characteristic is selected and the rear acoustic resistive member is welded and fixed to the ring projection 15 by using an ultrahigh frequency signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a directional dynamic microphone unit mainly used for vocal and loud sound.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view of a conventional directional dynamic microphone unit. In FIG. 4, reference numeral 1 is a cylindrical equalizer, 2 is a spherical diaphragm having a nearly disk shape, and 3 is a cylindrical voice coil. The front end is adhesively fixed to the diaphragm 2 and the rear end is ring-shaped. It is inserted in the gap between the pole piece 5 and the magnetic yoke 4.

Reference numeral 6 is a ring-shaped magnet closely attached between the magnetic pole piece 5 and the magnetic yoke 4. The magnetic yoke 4, the magnetic pole piece 5 and the magnet 6 are integrally resin-molded with a synthetic resin to form an acoustic yoke 7. There is. The outer periphery of the diaphragm 2 is adhesively fixed to the upper portion of the acoustic yoke 7.

Reference numeral 8 denotes a cylindrical synthetic resin case, which forms an internal air chamber 9 and a phase-shifting circuit acoustic terminal 10 together with the acoustic yoke 7, and an acoustic wave for the phase-shifting circuit is provided on the outer periphery of the phase-shifting circuit acoustic terminal 10. The resistance material 11 is adhesively fixed.

Reference numeral 14 denotes a rear sound hole which is provided on the bottom surface of the synthetic resin case 8 and communicates with a rear air chamber 13 formed by the rear case 12 and the synthetic resin case 8, and 16 covers the rear sound hole 14. It is a rear acoustic resistance material attached in a shape.

The output frequency characteristic in the above conventional example is controlled by the value of the acoustic resistance of the rear acoustic resistance material 16 including the inner diameter of the rear sound hole 14 and the value of the acoustic resistance of the phase shift circuit acoustic resistance material 11. Is.

[0007]

However, in the above-mentioned conventional directional dynamic microphone unit, when it is intended to realize a directional dynamic microphone unit having performance in which the output frequency characteristic is changed,
It is necessary to change the rear sound hole 14 and the rear acoustic resistance material 16 together with the phase-shifting circuit acoustic resistance material 11.

The phase shift circuit acoustic resistance material 11 and the rear acoustic resistance material 16 are made of woven fabric or non-woven fabric made of synthetic fiber, and it is relatively easy to select materials having different acoustic resistance values. However, changing the rear sound hole 14 changes the synthetic resin case 8, which necessitates the production of a new molding die, and the directional dynamic having the performance with the output frequency characteristic changed. There is a problem in that it is necessary to make a large investment for newly manufacturing a molding die for the synthetic resin case 8 each time an attempt is made to realize a microphone unit.

The present invention solves the above-mentioned conventional problems, and it is an object of the present invention to provide an excellent directional dynamic microphone unit having a performance in which the output frequency characteristic is changed.

[0010]

In order to achieve the above object, the present invention provides a plurality of ring-shaped projections having different inner diameters at the bottom of a synthetic resin case, and the innermost of the plurality of ring-shaped projections. A rear sound hole provided inside the circumference, a rear acoustic resistance material placed on a plurality of ring-shaped projections, and an outer diameter of the ring-shaped projection having an inner diameter dimension that makes a target acoustic resistance value. The ultrasonic welding horn corresponding to the above is applied from above the rear acoustic resistance material, and the rear acoustic resistance material is ultrasonically welded and fixed to a part of the ring-shaped projection of the synthetic resin case.

[0011]

Therefore, according to the present invention, the ultrasonic welding horn having the same outer diameter and the same size as the ring-shaped projection having the value of the acoustic resistance that gives the desired output frequency characteristic is applied from above the rear acoustic resistance material, By fixing the acoustic resistance material to the ring-shaped protrusions by ultrasonic welding, it is possible to eliminate the need for a new mold for the synthetic resin case, and it is possible to change the output frequency characteristics without making a large investment. Have.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a directional dynamic microphone unit according to an embodiment of the present invention, and FIG. 2 is a partial sectional view of the same directional dynamic microphone unit. 1 and 2, 1 is a cylindrical equalizer, 2
Is a spherical diaphragm close to a disk shape, 3 is a cylindrical voice coil, the front end of which is adhered and fixed to the diaphragm 2, and the rear end of the diaphragm and the outer peripheral surface of the ring-shaped magnetic pole piece 5 Of the diaphragm 2 inserted in the gap between the inner peripheral surfaces of the magnetic yokes 4 of
Receives an acoustic signal, the voice coil 3 is displaced, thereby inducing an output signal in the voice coil 3.

Reference numeral 6 is a ring-shaped magnet which is closely attached between the rear surface of the pole piece 5 and the surface on the magnetic yoke 4. Reference numeral 7 denotes an acoustic yoke, and the magnetic yoke 4, the magnetic pole pieces 5, and the magnet 6 are integrally resin-molded with a synthetic resin to form a magnetic circuit. The outer periphery is adhesively fixed.

Reference numeral 8 denotes a cylindrical synthetic resin case, which forms an internal air chamber 9 and a phase shift circuit acoustic terminal 10 together with the acoustic yoke 7.

Reference numeral 11 denotes an acoustic resistance material for a phase shift circuit, which is made of a woven cloth or a non-woven fabric made of synthetic fiber, and is adhered to the outer periphery of the phase shift circuit acoustic terminal 10 formed by the acoustic yoke 7 and the synthetic resin case 8. It is fixed.

Reference numeral 12 is a rear case, and 13 is a rear air chamber formed by the synthetic resin case 8 and the rear case 12. 1
Reference numeral 4 denotes a rear sound hole connecting the inner air chamber 9 and the rear air chamber 13 provided on the bottom surface of the synthetic resin case 8, and 15 denotes the synthetic resin case 8
Is a plurality of ring-shaped projections having different inner diameters provided around the rear sound hole 14 on the bottom surface of the.

Reference numeral 16 is a rear acoustic resistance material made of a woven cloth or a non-woven cloth made of synthetic fiber, and has a ring-shaped projection 15
Is fixed by ultrasonic welding to a part of the above, and is provided so as to cover the rear sound hole 14.

According to the structure of the above embodiment, the material of the phase-shifting circuit acoustic resistance material 11, which is an element for controlling the output frequency characteristic,
Among the three items of the material of the rear acoustic resistance material 16 and the inner diameter of the rear sound hole 14, it is the value of the acoustic resistance of the rear acoustic resistance material 16 that contributes most to the control of the output frequency characteristic.
When the material of the rear acoustic resistance material 16 is uniform, the value of the acoustic resistance increases or decreases in inverse proportion to the area ratio of the rear sound hole 14.

An ultrasonic welding horn matching the outer diameters of a plurality of ring-shaped projections 15 provided on the outer side of the rear sound hole 14 at the bottom of the synthetic resin case 8 is applied to the rear acoustic resistance material 16 to make the rear acoustic resistance. By fixing the resistance material 16 to the ring-shaped projection 15 by ultrasonic welding, the inner diameter of the ring-shaped projection 15 becomes the inner diameter of the rear sound hole 14. The inner diameter of the rear sound hole 14 increases, and the value of the acoustic resistance of the rear acoustic resistance material 16 decreases in inverse proportion to the area ratio.

Along with this, it is possible to obtain a directional dynamic microphone unit having a performance in which the output frequency characteristic is changed, without requiring a large investment for newly manufacturing a molding die for the synthetic resin case 8. ..

For example, assuming that FIG. 3 shows the change of the output frequency characteristic according to the present embodiment, the innermost side of the ring-shaped protrusion 15 (solid line in the drawing) and the second ring-shaped protrusion from the inner side. No. 15 (broken line in the drawing) and the third ring-shaped projection 15 from the inner peripheral side (one-dot broken line in the drawing) have the effect that the output frequency characteristics can be easily changed.

The output frequency characteristic of 0 ° in FIG. 3 is the output frequency characteristic when the diaphragm 2 of the directional dynamic microphone unit is oriented in the direction of the acoustic input signal, and the output frequency characteristic of 180 ° is the directional dynamic. It is an output frequency characteristic when the diaphragm 2 of the microphone unit is directed in the direction opposite to the acoustic input signal.

[0024]

As is apparent from the above embodiment, the present invention provides a plurality of ring-shaped projections having different inner diameters on the bottom of a synthetic resin case, and selects the ring-shaped projection according to a desired output frequency characteristic. Since the ultrasonic welding horn that matches the outer diameter of the ring-shaped projection is applied from above the rear acoustic resistance material placed on the ring-shaped projection, the rear acoustic resistance material is fixed by ultrasonic welding to the ring-shaped projection. The directional dynamic microphone unit having the performance in which the output frequency characteristic is changed can be easily obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a directional dynamic microphone unit according to a first embodiment of the present invention.

FIG. 2 is a partial sectional view of the same directional dynamic microphone unit.

FIG. 3 is an output frequency characteristic diagram of the same directional dynamic microphone unit.

FIG. 4 is a sectional view of a conventional directional dynamic microphone unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Equalizer 2 Vibration plate 3 Voice coil 4 Magnetic yoke 5 Magnetic pole piece 6 Magnet 7 Acoustic yoke 8 Synthetic resin case 9 Internal air chamber 10 Phase shift circuit acoustic terminal 11 Acoustic resistance material for phase shift circuit 12 Rear case 13 Rear air chamber 14 Rear Sound hole 15 Ring-shaped protrusion 16 Rear acoustic resistance material

Claims (1)

[Claims] 1. A magnetic circuit integrally formed of synthetic resin with a pot-shaped magnetic yoke, a ring-shaped magnetic pole piece, a ring-shaped magnet and an acoustic yoke, and an outer peripheral edge fixed to the acoustic yoke. A diaphragm, a voice coil having a front end fixed to the diaphragm and a rear end inserted in a gap between the outer peripheral surface of the magnetic pole piece and the inner peripheral surface of the magnetic yoke, and the internal yoke together with the acoustic yoke. A directional dynamic microphone unit including a synthetic resin case which is formed and has a plurality of ring-shaped projections having different inner diameters on the bottom surface, and a rear acoustic resistance material ultrasonically fixed to a part of the ring-shaped projections.