JPS5852799Y2 - speaker - Google Patents

Description

[Detailed explanation of the idea] This invention relates to speakers.

In a conventional speaker having a circular flat diaphragm, the front end of the voice coil bobbin B is connected to the annular portion of the circular flat diaphragm A corresponding to the node at the time of the first resonance, as shown in Fig. 1. Alternatively, although not shown, the first resonance can be eliminated by connecting the front end of a cone connected to the voice coil bobbin B to a portion corresponding to the node to drive the circular flat diaphragm A. , the peak-dip in the sound pressure characteristics of the speaker caused by resonance was eliminated.

In addition, in the same figure, C is the voice coil, D is the damper, and E is the voice coil.
, F is yoke, G is magnet, H is center pole, J
is the frame, K is the reinforcing ring, and L is the edge.

A mathematical analysis of the structure for eliminating the primary resonance of the speaker having the circular flat diaphragm A is as follows.

Distance from the central axis to any position; 19 Distributed driving force;
F(r) is a reference function representing the m-th order axisymmetric bending vibration mode of the diaphragm; if s m (r), the driving point admittance Y at the time of the first resonance of the diaphragm is generally Y = fE 1(rXr )d r −(
1), and if the nodal circle in the first resonance is rl, then the reference function is! E 1 (r +) = O...).

In the above-mentioned conventional speaker, connecting and driving the front end of the voice coil bobbin B to the annular portion corresponding to the node of the first resonance is achieved by the distributed drive function F(r) of the above equation (1).
This corresponds to multiplying δ(r−rl) by δ(r−rl). Therefore, in the speaker having the above structure, the driving point admittance at the first resonance is as follows, and the first resonance can be eliminated.

However, in the above-mentioned speaker, Fig. 2 shows its resonance mode, and the effect of the first resonance on the sound pressure characteristics, that is, the peak dip that appears near the first resonance frequency flo (indicated by a in Fig. 4). ) can be removed as shown by the broken line in the same figure, but the second-order resonance, whose resonance mode is shown in Fig. 3, and resonances of higher order can cause peak dips (see Fig. 4) on the sound pressure characteristics. b indicates a peak dip due to the second-order resonance), and the reproduction limit of the speaker is determined by the second-order resonance frequency f20.

Therefore, the purpose of this invention is to eliminate not only the first-order resonance but also the peak dip in the sound pressure characteristics caused by the second-order resonance, and to achieve a wide reproduction band with smoothed sound pressure characteristics. The purpose is to provide speakers.

If two driving positions are set in an annular manner on a circular flat diaphragm so that the driving point admittance at that time becomes

If the settings are made so that the relationship holds true, the second
The peak dip b occurring in the sound pressure characteristics at the next resonance frequency f20 becomes smaller as shown by the solid line in FIG.

However, in the figure, the dashed line indicates the conventional peak dip.

And, the above relationship means that the driving circle diameter is rl'* as described above.
Not limited to the case where two r2' are defined, the front ridge 5).

Two or more can be set as long as formula (6) is simultaneously satisfied.

That is, a plurality of drive circle diameters rl' tr2- that satisfy
By selecting and driving the position of the arm (where m is an integer of 2 or more), the peak dip a at the first resonance frequency flo is removed from the sound pressure characteristics, and the peak dip at the second resonance frequency f20 is removed. dip b
can also be reduced.

This invention was made based on the above principle, and a first embodiment thereof is shown in FIG.

That is, in this speaker, the front ends of the two cones 2 and 3 are connected to the circular flat diaphragm 1 at a position with a circular diameter r1'*r2' that satisfies the above formula (7), and the front ends of the two cones 2. 3 is connected to the front end of the voice coil bobbin 4.

In this way, the 2 parts provided at the front end of the voice coil bobbin 4
fE1(r)FCr)(δ(r-r1')+δ(
r r2') Since the drive point was set to arm0, that is, the drive point admittance was zero at the nodal circle diameter of the first resonance mode.
Not only can the secondary resonance be eliminated, but also the driving positions of the two cones satisfy Since the driving positions of the two cones 2.3 are set so as to be smaller than in the case of the conventional driving example, the peak dip in the sound pressure characteristics due to the second resonance can be reduced compared to the conventional structure. It is possible to achieve a speaker with a wider reproduction band.

The number of the cones 2.3 is not limited to two as described above, but may include a plurality of driving circle diameters r satisfying the above (7 widths).
When setting l' s r 2', . 5 is the edge, 6 is the voice coil,
8 is a frame.

A second embodiment of this invention is shown in FIG.

That is, the speaker with is located at one position (7th
The front end of the voice coil bobbin 4' is connected to the side with the circle diameter r1' in the figure), and the front end of the voice coil bobbin 4' is connected to the side with the circle diameter r1' in the figure
2' side) to connect the front end of the cone 7.

The rear end of this cone 7 is connected to the middle body of the voice coil bobbin 4'.

The connection positions of the cone 7 and the voice coil bobbin 4' with respect to the circular flat diaphragm 1 may be reversed to the above case, and the number of cones 7 is not limited to one; Multiple driving circle diameters rI'*r2',...
・When setting rm', connect the voice coil bobbin to one of the diameter portions, and connect the remaining diameter portion to the middle body of the voice coil bobbin with multiple cones. Good too.

With this configuration, the front end of the voice coil bobbin 4' can be directly connected to one driving position on the circular flat diaphragm 1, which facilitates manufacturing.

Other effects are similar to those of the first embodiment.

As mentioned above, the speaker of this invention has the following equation: B l (r) t B 2 (r) ; 'Next,
A reference function similar to r) representing the second-order axisymmetric bending vibration mode; distributed driving force rl; a plurality of circle diameters r,' on a circular flat diaphragm that satisfies the conditions of the nodal circle diameter of the first-order resonance;
+r2's..., r' (m is an integer of 2 or more) is the drive position, which not only eliminates the first-order resonance but also reduces the second-order resonance, smoothing the sound pressure characteristics over a wide band. This has the effect of making it possible to create a speaker with a wide reproduction band.

[Brief Description of the Drawings] Figure 1 is a partial cross-sectional perspective view showing a conventional example, Figures 2 A and B are diagrams showing the first resonance mode of a circular flat diaphragm, and Figure 3 A and B are circular Figure 4 shows the sound pressure characteristics of the conventional speaker shown in Figure 1. Figure 5 shows the sound pressure characteristics of the speaker of this invention. 6 is a half longitudinal sectional view showing a first embodiment of this invention, and FIG. 7 is a half longitudinal sectional view showing a second embodiment of this invention. 1... Thin flat plate-shaped diaphragm, 2.3.7... Cone 5;
4,4'...Voice coil bobbin, 5...Edge,
6...Voice coil, 8-frame.

Claims (3)

[Scope of utility model registration request] (1) Multiple circular diameters r1' on the circular flat diaphragm that satisfy the conditions
s r 2',...+ryl (m is an integer of 2 or more)
A speaker whose driving position is at the position of . (2) The speed force according to claim O), wherein the driving position is driven by a plurality of cones provided at the front end of the voice coil bobbin. (3) The speaker according to claim 0, wherein the driving position is driven by the front end of the voice coil bobbin and a plurality of cones provided in the middle body of the voice coil bobbin.