JPS6338634Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention relates to an MFB type speaker, and more specifically, it aims to improve the vibration balance of the diaphragm.
Regarding MFB type speakers.

The MFB type speaker controls the movement of the vibration system by feeding back a voltage proportional to the movement of the vibration system, such as the diaphragm of the speaker, to the input of the amplifier that is the drive system. The vibration system is equipped with a vibration pickup. Most of the most well-known MFB type speakers have a vibration pickup fixed to the diaphragm, but when considering the vibration motion of the diaphragm, it is important to note that the motion balance of the diaphragm equipped with the vibration pickup is not necessarily sufficient. No, no.

For example, in the case of a speaker with a thin flat diaphragm shown in FIG. 1, one end of a bobbin 2 is fixed to the center of the diaphragm 1, and the voice coil 3 wound around the bobbin An input signal is supplied via an input tinsel wire 5 extending from an input terminal 4, and the diaphragm 1 is driven. This vibration of the diaphragm 1 is detected by a vibration pickup 6 fixed to the diaphragm 1, and is led to an output terminal 8 via an output tinsel wire 7.
It is fed back to the amplifier circuit.

In such a speaker, if the center of gravity is not on the center line of the diaphragm, or in other words, on the center line of the diaphragm along the direction of sound radiation (hereinafter referred to as the sound axis), the vibration movement of the diaphragm will occur. The balance may not be maintained and rolling may occur. For this reason, the input tinsel wire 5 and the output tinsel wire 7 are centered on the sound axis.
Static balance can be maintained if they are placed 180 degrees apart, but the weight balance is disrupted due to the fact that the vibrating pickups are attached.

Therefore, this idea was designed to keep the diaphragm balanced and prevent rolling even when a vibration pickup is attached to the diaphragm. The device is characterized in that a vibration pickup and a balancer are arranged along the imaginary radiation of the book and on the resonance node of the diaphragm.

Hereinafter, the embodiment shown in FIGS. 2 to 4 to which the configuration of this invention is attached will be described. First, a circular planar diaphragm indicated by the reference numeral 10 in FIGS. The voice coil bobbin 12 is fitted and integrated with an adhesive, and the voice coil 13 is wound around the voice coil bobbin 12. A protrusion 11a is formed concentrically with these protrusions 11 at approximately the center in the radial direction, and a protrusion 11b is also formed on the outer periphery of the flat diaphragm 10 around the outer periphery of this protrusion 11a. Three protrusions 11c are equally spaced radially to intersect with the protrusions 11, 11a, and these protrusions 11a, 11c extend along radial lines and virtual circles to be described later.

The periphery of this flat diaphragm 10 is supported by a speaker frame 15 via an edge 14, and a driver unit 1 is mounted in the center of the speaker frame 15.
6 is fixed, and the voice coil bobbin 1 is inserted between the air gap of the driver unit 16.
2 voice coils 13 are located.

Furthermore, the speaker frame 15 has an input terminal 1.
7 is provided, and an input tinsel wire 18 is extended from this input terminal 17 to the voice coil 13, and the voice coil bobbin 12 on which the voice coil 13 is wound has two dampers 19 at its intermediate portion.
is supported by the speaker frame 15 by.

On a virtual circle K connecting resonance nodes drawn with the acoustic axis of the plane diaphragm 10 as the center O, and
Imagine the book's rays H at equal angular intervals in the radial direction from the center O, and place a vibration pick-up 2 such as a bimorph on the back side of the diaphragm at the intersection _R1 of the imaginary circle K and the rays H.
0 is fixed, and its output tinsel wire 21 is connected to an output terminal 22 provided on the speaker frame 15. The virtual circle K is on the circle formed by the protrusions 11a, the radiation H is located on the protrusions 11c, and the protrusions 11c are cut between the protrusions 11.

Further, at other intersection points R ₂ and R ₃ , counterweights, so-called balancers 23, are respectively fixed to the back side of the diaphragm. Vibration pickup 20, balancer 23
is formed on the back side considering the appearance of the diaphragm 10, but it may be formed on the front side functionally.

This balancer 23 prevents rolling caused by the unbalanced weight of the vibrating pickup 20 when the planar diaphragm 10 makes a piston movement, so its size and weight are equal to those of the vibrating pickup 20.
In terms of manufacturing, thick portions are formed partially and integrally provided when the diaphragm 10 is molded.

Since the MFB type speaker of this invention has the above-described configuration, the vibration of the diaphragm is detected by the vibration pickup 20 and fed back to the input side of the amplification system. By being located on the node, resonance occurring at the secondary resonance frequency is not detected as a vibration signal, and the piston motion is well balanced.

As is clear from the above explanation, this idea
According to the MFB type speaker, a vibration pickup is installed on the resonance node of the diaphragm, and a balancer is installed concentrically with the vibration pickup at equal intervals, so the vibration pickup does not pick up the resonance phenomenon, and the vibration of the diaphragm is It detects accurately and is well-balanced, so no rolling phenomenon occurs.

[Brief explanation of the drawing]

Fig. 1 is a schematic side sectional view of a conventional MFB type speaker, Fig. 2 is a schematic side sectional view of the MFB type speaker according to this invention, and Fig. 3 is a rear view of the diaphragm showing the positions of the vibration pickup and balancer. , FIG. 4 is a sectional view taken along the line of FIG. 3. 10...Diaphragm, 12...Voice coil bobbin, 13...Voice coil, 14...Edge, 1
5... Speaker frame, 16... Driver unit, 17... Input terminal, 18... Input tinsel wire,
19...Damper, 20...Vibration pickup, 2
1... Output tinsel wire, 22... Output terminal, 23...
balancer.

Claims (1)

[Scope of utility model registration request] Constructed by attaching a vibration pickup to the diaphragm.
The MFB type speaker is characterized in that a vibration pickup is installed on a virtual ray centered on the center line of the diaphragm and on one resonance node, and balancers are placed on other nodes. MFB type speaker.