JP2546339Y2 - Speaker - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a loudspeaker having two magnetic circuits for driving a diaphragm at the front and rear of the diaphragm.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, there has been known a twin-drive type loudspeaker in which a diaphragm driving magnetic circuit is provided at two places, front and rear of a diaphragm. In FIG. 1, reference numeral 1 denotes a frame, 2 denotes a diaphragm, and the diaphragm 2 is elastically supported by the frame 1 via an edge 3. Reference numeral 4 denotes a first magnetic circuit, which includes a value ferrite permanent magnet 5, a bottom plate 6, and an upper plate 7. Reference numeral 9 denotes a second magnetic circuit, which includes a value ferrite permanent magnet 10, a bottom plate 11, and an upper plate 12. 8 is penetrated by the vibrating plate 2 and one end is attached to the tip of the bottom plate 6 of the first magnetic circuit 4;
A coupling spacer 13 having the other end attached to the tip of the bottom plate 11, a fixing screw 13 for connecting the first magnetic circuit 4 and the second magnetic circuit 9, and a magnetic gap 15 of the first magnetic circuit 4. And the first connected to the diaphragm 2
The first coil bobbin 14 is elastically supported by a first damper 16. Reference numeral 17 denotes a second coil bobbin which is interposed in a magnetic gap 18 of the second magnetic circuit 9 and is elastically supported by a second damper 19;

When an electric signal is applied to the voice coil wound around the first coil bobbin 14 and the second coil bobbin 17, the diaphragm 2 is driven by the action of the first magnetic circuit 4 and the second magnetic circuit 9. At this time, assuming that the driving force for driving the diaphragm 2 generated by the first magnetic circuit 4 is F1, F1
= B1 ・ L1 ・ I1 (B1; magnetic flux density in the air gap of the first magnetic circuit 4, L1; length of the voice coil wound around the first coil bobbin 14, I1; current flowing through the voice coil). Similarly, assuming that a driving force for driving the diaphragm 2 generated by the second magnetic circuit 9 is F2, F2 = B2 · L2
I2 (B2; magnetic flux density in the air gap of the second magnetic circuit 9, L
2; length of the voice coil wound around the second coil bobbin 17, I2; current flowing through the voice coil).

[0004]

In the case of a twin-drive type speaker, it is desirable that the driving force F1 and the driving force F2 be equal, and in addition, the elastic force of the first damper 16 and the second damper 19 is also equal. desirable. Therefore, the first magnetic circuit 4, the first coil bobbin 14, and the second
The magnetic circuit 9 and the second coil bobbin 17 need to use the same specifications in order to generate the same driving force, but the second magnetic circuit 9 disposed on the sound wave emitting surface side of the diaphragm 2
However, there is a problem that sound waves are disturbed as an obstacle, and the frequency characteristics are degraded.

In order to solve the above problem, it is conceivable to use a rare earth permanent magnet having a high energy product instead of the value ferrite permanent magnet to reduce the size of the second magnetic circuit. Is expensive compared to a value ferrite permanent magnet, and has a problem that it leads to a significant cost increase.

[0006]

According to the present invention, there is provided a loudspeaker having two diaphragm driving magnetic circuits at the front and rear of a diaphragm. The diameter of the coil bobbin installed on the magnetic circuit in front of the diaphragm is set smaller than the diameter of the coil bobbin installed, and the magnetic circuit in front of the diaphragm is smaller than the magnetic circuit behind the diaphragm. Is proposed.

[0007]

With the configuration described above, the size of the magnetic circuit in front of the diaphragm can be smaller than that of the magnetic circuit behind the diaphragm.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 and 2 show the speaker of the present invention, the same parts as those of the conventional speaker are denoted by the same reference numerals, and description thereof will be omitted. As described above, on the assumption that the driving force F1 generated by the first magnetic circuit 4 is equal to the driving force F2 generated by the second magnetic circuit 9, F1 =
It suffices if F2 = B1 · L1 · I1 = B2 · L2 · I2. Therefore, B1 (the magnetic flux density in the air gap of the first magnetic circuit 4), L1 (the length of the voice coil wound around the first coil bobbin 14), I1 (the current flowing through the voice coil), B2 (the second magnetic circuit) 9), L2
If (the length of the voice coil wound around the second coil bobbin 17) and I2 (current flowing through the voice coil) are set, the diameter of the coil bobbin is changed, and the size of the first magnetic circuit 4 or the second magnetic circuit is changed. It is possible to change The present invention focuses on this point, and as shown in FIG.
The feature is that the diameter of the coil bobbin 17 is reduced, and as a result, the diameter D and the protrusion amount H of the second magnetic circuit 9 are reduced. Since the diameter of the first coil bobbin 14 and the diameter of the second coil bobbin 17 are different, the joint spacer 2
Of course, the diameter of the circumferential groove b in which the second coil bobbin 17 fits is smaller than the diameter of the circumferential groove a in which the first coil bobbin 14 fits at zero.

[0009]

According to the present invention, as described in detail above, according to the present invention, a speaker having a magnetic circuit for driving a diaphragm at two places in front of and behind a diaphragm is installed in a magnetic circuit behind the diaphragm. The diameter of the second coil bobbin installed in the magnetic circuit in front of the diaphragm is set smaller than the diameter of the first coil bobbin, so that the magnetic circuit in front of the diaphragm is smaller than the magnetic circuit behind the diaphragm. As a result, the size of the second magnetic circuit can be reduced, the deterioration of the frequency characteristics due to the disturbance of the sound wave radiation can be reduced, the speaker can be reduced in size by reducing the amount of protrusion of the second magnetic circuit, the weight of the speaker can be reduced, and the cost can be reduced. It has various effects such as downtime.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing the structure of the speaker of the present invention.

FIG. 2 is a perspective view showing the structure of the speaker of the present invention.

FIG. 3 is a side sectional view showing the structure of a conventional speaker.

[Explanation of symbols]

 Reference Signs List 1 frame 2 diaphragm 3 edge 4 first magnetic circuit 5 value ferrite permanent magnet 6 bottom plate 7 upper plate 8 coupling spacer 9 second magnetic circuit 10 value ferrite permanent magnet 11 bottom plate 12 upper plate 13 fixing screw 14 first coil bobbin Reference Signs List 15 magnetic gap 16 first damper 17 second coil bobbin 18 magnetic gap 19 second damper 20 joint spacer

Claims (1)

(57) [Scope of request for utility model registration] 1. A loudspeaker having a diaphragm driving magnetic circuit at two places in front of and behind a diaphragm, wherein a magnetic circuit in front of the diaphragm is larger than a diameter of a coil bobbin installed in a magnetic circuit behind the diaphragm. A speaker characterized in that the diameter of a coil bobbin installed in the diaphragm is set small, and a magnetic circuit in front of the diaphragm is made smaller than a magnetic circuit behind the diaphragm.