JPS58138198A - Loudspeaker - Google Patents

Abstract

PURPOSE:To obtain excellent characteristic without the influence of the edge to the resonance frequency and oscillation mode inherent to the diaphragm in an loudspeaker which drives the node of the oscillation mode of the diaphragm, by supporting the node with the edge. CONSTITUTION:A flat circular diaphragm 1 is joined with the expanded edge of a driving cone 3 at the node of the primary dividing oscillation mode, and supported by one end of an edge 2 at the node of the primary dividing oscillation mode. The other end of the edge 2 is fixed to a frame 6 along the back surface of the diaphragm 1. When the diaphragm 1 is supported by the edge 2 through the node in this way, changes in the inherent resonance frequency and oscillation mode related to the primary dividing oscillation of the diaphragm 1 are eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speaker that drives vibration mode nodes of a diaphragm, and more particularly to a speaker in which the position at which the diaphragm should be supported by the edges is improved.

FIG. 1 shows a conventional flat speaker. This speaker consists of a flat circular diaphragm 1, an edge 2 glued to the outer periphery of the diaphragm 1, and a cone-shaped diaphragm whose enlarged diameter end is joined to the node of the primary divided vibration mode of the diaphragm 1. A driving cone 3, a voice coil 4 that is joined to the end of the reduced diameter part of the driving cone 3 and drives the diaphragm 1 by -C through the driving cone 3, and a voice coil 4 that is bonded to the outer peripheral wall of the voice coil 4. The damper 5 supports the voice coil 4, a frame 6 to which the damper 5 and the edge 2 are fixed, and a magnetic circuit 7 for driving the voice coil 4.

It is known that a speaker having such a structure can expand the reproduction frequency band as a speaker by driving the nodes of the vibration mode of the diaphragm 1. In other words, when the node of the axially symmetrical first division vibration mode is driven, the -order division vibration mode is canceled out, and the sound pressure characteristics near the frequency f1 become flat, so the frequency is approximately four times the frequency f1 of the -order division vibration. The sound pressure characteristics of the second-order divided vibration frequency f, which occurs at the frequency f, can also be made flat.

By the way, the position of the node of the above-mentioned -order divided vibration mode is determined as follows. That is, according to the classical theory of a flat circular diaphragm, the position of the node of a diaphragm with a boundary condition of peripheral freedom is, if the radius of the diaphragm is a and the radius of the node is fr, then r at fl is approximately equal to a. It becomes 0.68 times (0.68 a in r).

However, in the conventional speaker, as mentioned above, the diaphragm 1 is supported by the edges 2 at its outer periphery, so the boundary condition of the diaphragm 1 is no longer free around the edges, and it is in a state of elastic support. . For this reason, the resonant frequency and vibration mode of the diaphragm itself change under the influence of edge 2,
Since fI decreases slightly, r also increases by 0.68 a (Mitsubishi Electric Branch Axis (Kuninaka, Hejima, Sakai) Vo
t, 54, no.

12 1980). There is a problem in that when r increases in this manner, the resonance frequency decreases.

The present invention has been made in view of the above points, and an object of the present invention is to provide a speaker in which the resonant frequency and vibration mode of the diaphragm itself are not affected by edges.

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

FIG. 2 shows a speaker according to the present invention. This speaker includes a flat circular diaphragm 1, a cone-shaped driving cone 3 whose enlarged diameter end is joined to the node of the primary division vibration mode of the diaphragm 1, and a cone-shaped drive cone 3 whose diameter-reduced end is joined to the node of the primary division vibration mode of the diaphragm 1. A voice coil 4 is joined to the diaphragm 1 and drives the diaphragm 1 via a driving cone 3, a damper 5 is bonded to the outer peripheral wall of the voice coil 4 and supports the coil 4, and the damper 5 is fixed. frame 6 and voice coil 4
It is equipped with a magnetic circuit 7 for driving.

In the speaker according to the present invention, the diaphragm 1 is supported by one end of the edge 2 at the location where the driving cone 3 is joined, that is, at the node of the primary division vibration mode. The other end of the edge 2 is fixed to a frame 6 along the back surface of the diaphragm 1.

When the diaphragm 1 is supported by the edges 2 through the above-mentioned nodes in this manner, the unique resonance frequency and vibration mode (eigenfunction) regarding the primary division vibration of the diaphragm 1 do not change. If the head is changed, the node r of the vibration mode corresponds to 0.68 a according to the classical theory (see Journal of the Acoustical Society of Japan (authored by Hejima, Suzuki, and Shindo), Vol. 34, No. 8, 1978).

Another embodiment of the invention is shown in FIG.

In this embodiment, the voice coil 4 is formed into a cylindrical shape so as to have the same diameter as the node of the primary divided vibration mode of the diaphragm l,
An example is shown in which the toe of this voice coil 4 is directly joined to the above-mentioned node position of the diaphragm 1.

In the above two embodiments, an example is shown in which a flat circular diaphragm is used, but the same effect can be obtained by using a cone-shaped or dome-shaped diaphragm.

In addition, although the above embodiment shows an example in which the nodes of the diaphragm are driven in the primary divided vibration mode, it can also be applied to a speaker that drives the nodes in the secondary or higher divided vibration modes, and similar effects can be obtained. Can be done.

As is clear from the above description, according to the present invention, in a speaker that drives the nodes of the vibration mode of the diaphragm, the nodes are supported by the edges, so that the resonance frequency and vibration mode specific to the diaphragm are controlled by the edges. This makes it possible to obtain a speaker with almost no influence, and therefore with excellent acoustic characteristics.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional flat speaker, FIG. 2 is a sectional view of a flat speaker according to the present invention, and FIG. 3 is a sectional view of a speaker according to another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Vibration plate, 2... Edge, 3... Driving cone, 4... Whisker coil, 5... Damper, 6...
・Frame, 7...Magnetic circuit. In the figures, the same reference numerals indicate the same or corresponding parts. Agent Makoto Kuzuno - Office Figure 1 Figure 2 Figure 3 Procedural amendment (voluntary) Commissioner of the Japan Patent Office 2, Title of invention Speaker 3, Person making the amendment Relationship to the case Patent applicant address Chiyoda-ku, Tokyo Marunouchi 2 Jto 12-3
．． ＞, 3 names (601) Mitsubishi Electric Corporation Representative Katayuni 8be 4, Agent address 12-3-5 Marunouchi 2-ro, Seventh generation IJi-ku, Tokyo Detailed explanation of the invention in the specification subject to amendment column. 6. Details of amendment (1) On page 2, line 18 of the specification, "The sound pressure characteristics at the divided vibration frequency f2 can also be made flat" is corrected to "The sound pressure characteristics up to the vicinity of the divided vibration frequency f2 can be made flat." (2) On page 3, line 11, “because it decreases” is corrected to “declines.” (3) Lines 13-14 of the same page: “And when it gets bigger”
``As mentioned above, conventional speakers have a large r.''
I am corrected. that's all

Claims (1)

[Scope of Claims] (1) A speaker comprising an edge that supports a diaphragm and a drive unit that drives a vibration mode node of the diaphragm, wherein the edge supports the node of the diaphragm. A speaker characterized by: (2) The speaker according to claim 1, wherein the nodes of the diaphragm are nodes of a primary divided vibration mode or a secondary or higher divided vibration mode. (8) The speaker according to claim 1 or 2, wherein the diaphragm has a flat plate shape, a cone shape, or a dome shape.