JPS58221599A - Dynamic loudspeaker - Google Patents

Abstract

PURPOSE:To obtain the flat frequency characteristics, by attaching a voice coil to a rectangular diaphragm with eccentricity and at the same time bonding the edge of the diaphragm further away from the voice coil to a frame. CONSTITUTION:A rectangular diaphragm 1 is driven with eccentricity by a voice coil, and a part of an edge member at the side further away from the voice coil is adhered to a frame. The length of the edge adhered part is selected to change the stiffness value of the edge part. The stiffness value at the side further away from the voice coil is set larger than that of the other side. Thus the diaphragm 1 has different amplitude values at its each point and produces all vibrations in-phase. Therefore no negation of vibrations due to adverse phase components is produced. This ensures the flat frequency characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrodynamic speaker configured to drive a rectangular diaphragm by a voice coil coupled to a position eccentric from the center of a long side of the rectangular diaphragm. The object of the present invention is to provide an electrodynamic speaker capable of flattening sound pressure frequency characteristics.

In general, audio equipment is increasingly becoming stereo, as seen in audio multiplexing television receivers and tape recorders with radio receivers, but using conventional round speakers results in thicker cents. . Therefore, since most of the audio equipment in which a speaker is housed has a rectangular parallelepiped structure, a speaker having a rectangular diaphragm has been developed, and attempts have been made to make the set more compact.

In particular, rectangular planar speakers have a diaphragm shape, the voice coil is eccentric from the center of the long side of the diaphragm, and the magnetic circuit on the back of the speaker is all moved to the edge of the frame, allowing radio reception with many mechanical parts such as motors. The aim is to improve the parts storage ratio of small audio equipment such as machine tape recorders and to make cents more compact.

1 and 2 show all conventional electrodynamic speakers of this type. In FIGS. 1 and 2, 7 is a yoke in which a center ball 9 is integrally formed, 6 is an annular magnet fixed on the yoke 7, and 6 is an annular plate fixed on the magnet 6. With these, plate 6
A magnetic circuit having an annular magnetic gap is formed between the inner peripheral surface of the center pole and the outer peripheral surface of the center pole. The magnetic circuit is fixed to the bottom surface of the frame 1o. 1 is a rectangular plane diaphragm, and this rectangular plane diaphragm 1 has an edge member 2.
is supported by the opening of the frame 10. A coil bobbin 3 is connected to a position eccentric from the center of the long side of the diaphragm 1. A voice coil 8 is wound around the coil bobbin 3, and the voice coil 8 is inserted into the magnetic gap. A damper 4 supports the voice coil bobbin 3. The third vibration mode at 600 Hz K when the driving force F from the voice coil BvC is applied to the rectangular plane diaphragm 1 in such an electrodynamic speaker is
Shown in the figure. However, in the above-mentioned electrodynamic speaker 7, since the shape of the edge member 2 is axially symmetrical, the stiffness of the two opposing sides is equal, and therefore the stiffness of both short sides shown in FIG. 3 is 1. ni 2 ni 1-
2, and with the driving force from the voice coil 8 coupled at a position eccentric from the center of the diaphragm, the diaphragm 1 experiences a rotational force around point P, as shown by the broken line. As a result, the sound pressures radiated from the left and right sides of the diaphragm 1 have opposite phases, using the point pl as a reference, so they cancel each other out, and the sound pressure frequency characteristics are 500Hz to 1.5 KHz, as shown in Figure 4.
The problem was that the entire structure was affected, the sound pressure decreased, and the flatness was lost.

The present invention solves these conventional drawbacks,
By fixing a part of the short side of the edge member far from the voice coil coupling position to a frame that follows the shape of the edge, the stiffness of both short sides of the edge member is made different, and the diaphragm receives the rotational moment. The structure is such that the sound pressure radiated in the opposite phase is eliminated and a flat frequency characteristic is obtained.

The present invention will be described below with reference to drawings of embodiments. 5 and 6 show one embodiment of the present invention, and in FIGS. 5 and 6, the same parts as in FIGS. 1 and 2 are given the same numbers. In the example, a part of the short side of the edge member 2 on the side far from the coupling position of the voice coil 8 that eccentrically drives the rectangular plane diaphragm 1 is fixed to the frame 1o by adhesive. That is, an edge adhesive part 10"i is provided on the frame 1o along the narrow edge of the roll, and this adhesive part 10
Also glue a part of the short side of the edge member to '. This edge adhesive part changes the fixed state of the edge by selecting its length e and width w1 to control its stiffness value, and the left and right stiffnesses are set to 1. To:
2, the value eK1>K2. Therefore, the edge portion farthest from the voice coil coupling position is in motion and is in vibration mode as shown in FIG. Although the amplitude values differ at the valley points on the diaphragm, they are all in phase, so there is no cancellation due to the opposite phase shown in the conventional example, and a speaker with flat sound pressure frequency characteristics as shown in Figure 8 can be realized. It is something.

Further, in the above embodiment, the edge shape was a roll shape, but the same effect can be expected even with other shapes, such as a wave shape, by providing the edge bonding portion 10''i that conforms to the shape.Also, In the above embodiment, the diaphragm was a flat diaphragm, but as shown in FIGS. 9 and 10, a rectangular cone diaphragm 11 also poses the problem of a decrease in sound pressure, but this problem can be completely eliminated. be.

As described above, according to the present invention, a part of the short side of the edge member on the side far from the voice coil coupling position is fixed to a frame that follows the shape of the edge. By varying the stiffness of the short sides, the diaphragm can be driven without receiving the full rotational moment, thereby reducing the sound pressure radiated in the opposite phase and flattening the frequency characteristics. has advantages.

[Brief explanation of drawings]

Fig. 1 is a top view of a conventional electrodynamic speaker, Fig. 2 is a cross-sectional view of the same speaker, Fig. 3 is a vibration mode diagram of the same speaker, Fig. 4 is a sound pressure frequency characteristic diagram of the same speaker, and Fig. 6 is a diagram of the same speaker. 6 is a sectional view of the speaker, FIG. 7 is a vibration mode diagram of the speaker, and FIG. 8 is a top view showing an embodiment of the speaker of the present invention.
The figure is a sound pressure frequency characteristic diagram of the same speaker, FIG. 9 is a top view showing another embodiment of the speaker of the present invention, and FIG. 10 is a sectional view of a main part of the same speaker. 1... Rectangular diaphragm, 2... Edge member, 3... Bobbin, 4... Damper, 5
...Top plate, 6...Magnet,
7... Balk, 8... Voice coil,
9...Center pole, 1o...Frame, 10'...Edge adhesion part. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4 Yutoshi Oka (lh) Figure 5 Figure 6 Figure 7 Figure 1 Figure 8 Ifi Freeze KCH WA9 Figure 110 Figure //2

Claims (1)

[Scope of Claims] (1) A rectangular diaphragm whose outer periphery is supported on a frame via an edge member is configured to be driven by a voice coil coupled to a position eccentric from the center of its long side, An electrodynamic speaker characterized in that a part of the short side of the edge member farthest from the voice coil coupling position is attached to the edge shape of the frame. (2) The edge member has a roll shape. An electrodynamic speaker according to claim 1, characterized in that the edge member has a corrugated shape. (4) Rectangular diaphragm The electrodynamic speaker according to claim 1, 2 or 3, characterized in that is a flat diaphragm. (6) The rectangular pickup plate is a rectangular cone diaphragm. An electrodynamic speaker according to claim 1, 2, or 3.