JPH0252917B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a flat speaker used in various types of audio equipment.

Conventional configuration and its problems Generally, a flat speaker is configured as shown in FIG.

That is, a frame 6 is connected to a magnetic circuit 5 formed by laminating and bonding a ring-shaped magnet 3 to a plate 2 having a center pole 1 and a ring-shaped plate 4, and a gasket is attached to the periphery of this frame 6. 7, an edge 8 such as a free edge is attached, and a flat diaphragm 9 is attached to this edge 8.
A drive cone 10 is coupled to the lower surface of the flat diaphragm 9, and a magnetic gap 1 of the magnetic circuit 5 is coupled to the center of the drive cone 10.
1 and a voice coil 12 that fits into the damper 1 is coupled to the voice coil 12 and held by a damper 13.

In such a planar speaker, the band is expanded to the second resonance by driving the node position of the first resonance mode of the plane diaphragm 9. However, the central part of the flat diaphragm 9 was experiencing abnormal resonance such as split resonance, which adversely affected the sound pressure frequency characteristics and caused significant peaks and dips in the high frequency range. 2a and 2c show the sound pressure frequency characteristics and second-order distortion of a conventional flat speaker. b and d show the sound pressure frequency characteristics and second distortion of a flat speaker in which the skin material of the flat diaphragm and the drive cone are made of relatively soft materials with high internal loss. Although this configuration eliminates the peak in the treble range, there are problems such as a decrease in the sound pressure level of the entire treble range and a significant increase in second-order distortion. There was also a structure in which the center of the plane diaphragm was cut out and filled with a foreign material that had a large internal loss, but this structure resulted in a decrease in external quality and
There were problems such as increased costs due to increased man-hours in the manufacturing process of the flat diaphragm, and a reduction in the high frequency reproduction frequency band due to a decrease in surface rigidity at the center of the flat diaphragm.

Purpose of the Invention The present invention eliminates the above-mentioned drawbacks of the conventional technology, and is capable of preventing abnormal resonance at the center of a plane diaphragm and flattening sound pressure frequency characteristics with an extremely simple structure. The purpose of this invention is to provide an effective planar speaker.

Structure of the Invention In order to achieve the above object, the present invention provides skin materials on both sides of a core material having a circular or non-circular cut portion in the center portion of the frame coupled to the magnetic circuit through an edge. A planar diaphragm is attached, and a voice coil that fits into the magnetic gap of the magnetic circuit is coupled to this planar diaphragm. With this structure, the strength and appearance quality of the planar diaphragm are not deteriorated. Flattening of sound pressure frequency characteristics can be achieved with a simple configuration.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Since the structure of the planar speaker is substantially the same as that shown in FIG. 1, only the planar diaphragm, which is a feature of the present invention, will be explained here.
FIG. 3 shows the structure of the flat diaphragm of the flat speaker of the present invention. That is, the center part 9b of the honeycomb-structured core material 9a is cut once using a cutting die, and then the center part 9 of the cut core material 9a is cut.
By fitting b into the original position, the core material 9a
A planar diaphragm 9 was formed by pasting aluminum skin materials 9c and 9d on top and bottom. In this case, there is no effect even if the positions of the core material 9a and the center portion 9b are shifted when inserting the center portion 9b of the core material 9a. Similarly, a diaphragm having the shape shown in FIG. 4 was formed using the same method. In FIG. 4, a is an example in which the center part 9b of the circular core material 9a is cut into a circular shape, and hereinafter b is an example in which the center part 9b of the circular core material 9a is cut.
c is the center part 9b of the circular core material 9a.
is oval, and d is the center 9 of the rectangular core material 9a.
b is a square, and e is the cut of the center part 9b at d.
45 degrees shifted, f is the center part 9b of the rectangular core material 9a is circular, g is the center part 9b of the rectangular core material 9a is elliptical, and h is the continuation of the straight line and circular arc at the periphery. The center part 9b of the core material 9a is square, i is the cut of the center part 9b at k shifted by 45 degrees, and j is the center part 9b of the core material 9a whose peripheral part is a continuous shape of straight lines and circular arcs. is circular, k is the center part 9b of the core material 9a having the same shape as j, and l is oval.
The central part 9b of the core material 9a having the same shape as h is cut into a shape similar to the outer shape. A remarkable effect was obtained when the cut diameter or dimension of the center portion 9b was 15% to 35% of the outer diameter or outer dimension of the flat diaphragm 9. By cutting the center part 9b of the core material 9a of the flat diaphragm 9, appropriate compliance is given near the center of the sound axis, and this compliance prevents abnormal resonance in the center at high frequencies. It caused a counter-resonance that canceled it out. Furthermore, the weight of only the center part 9b of the core material 9a, which is independent of the weight of the flat diaphragm 9, exists in the center, which causes a loss in the amplitude of the flat diaphragm 9 of the flat speaker. This means that the splitting vibrations of are suppressed. A similar experiment was conducted on core material 9a whose cut portions were discontinuous. Fig. 5 shows this embodiment, and a, b, and c indicate four points on a circular arc, two points on a circular arc, and four points on a rectangular shape at the center 9b of a circular core material 9a. Discontinuous parts left as uncut parts, d, e, f are rectangular core materials 9
The center part 9b of a is made discontinuous by leaving 2 points on an ellipse, 4 points on an arc, and 4 points on a rectangular shape, and g, h, and i are discontinuous with the peripheral parts being straight lines. The center part 9b of the core material 9a, which has a continuous arc shape, is made discontinuous by leaving 4 points in a rectangular shape and 4 points on the arc, leaving 2 uncut parts in an elliptical shape, and the remaining The part is penetrated. In this case, there was a significant effect when the discontinuous portion was 30% or less. Furthermore, similar experiments were conducted for a case where the cut portion was a part of the core material 9a in the thickness direction. FIG. 6 shows this embodiment, in which a shows a front view of the core material 9a, and b and c show cross-sectional views of the core material 9a. b is an example in which cuts were made from one side in the thickness direction, and c is an example in which cuts were made in both thickness directions. In this case, the effect was achieved when the depth of the cut was 50% or more of the thickness of the core material 9a.

The sound pressure frequency characteristics and second-order distortion of a flat speaker using this flat diaphragm are shown in FIGS. 7 and 8. FIG. 7 shows a circular planar speaker, and FIG. 8 shows a rectangular planar speaker. In each drawing, e, g, f, and h indicate sound pressure frequency characteristics and second-order distortion. Compared to the conventional flat speaker shown in FIG. 2, the peak in the treble range is significantly lowered, the overall sound pressure level in the treble range is not lowered, and there is little distortion. Although the planar speaker shown in FIG. 1 has the voice coil 12 coupled to the planar diaphragm 9 via the drive cone 10, the present invention also includes a configuration in which the voice coil 12 is directly coupled to the planar diaphragm 9. Inventions can achieve the same effect.

Effects of the Invention Since the planar speaker of the present invention is configured as described above, it is possible to provide appropriate compliance to the center of the diaphragm, which is a cause of abnormal resonance in the high frequency range, with a simple configuration, and to prevent abnormal resonance such as split resonance. can cause resonance that cancels out the Therefore, the peak in the high frequency range is removed, resulting in a flat frequency characteristic. Furthermore, since the center portion is also made of the same material, the rigidity does not deteriorate, the sound pressure level in the high frequency range does not decrease, the appearance quality does not deteriorate, and productivity is high, making it of great industrial value.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing a general flat speaker.
Figure 2 is a characteristic diagram of the sound pressure frequency characteristics and second-order distortion of a conventional flat speaker, Figure 3 is an exploded perspective view of a flat diaphragm in an embodiment of the flat speaker of the present invention, and Figures 4 a to l. , Fig. 5 a-i, Fig. 6 a,
b and c are top views and cross-sectional views showing examples of the core material of the flat diaphragm of the present invention, and Figures 7 and 8 show the sound pressure frequency characteristics and second-order distortion of the flat speaker of the present invention. It is a characteristic diagram. 1...Center pole, 2...Plate, 3...
...Magnet, 4...Plate, 5...Magnetic circuit, 6...Frame, 7...Gasket, 8...
Edge, 9...Plane diaphragm, 9a...Core material, 9
b...Central part, 9c, 9d...Skin material, 10...
...Drive cone, 11...Magnetic gap, 12
...Voice coil, 13...Damper.

Claims (1)

[Claims] 1. A planar diaphragm in which skin materials are attached to both sides of a core material with a circular or non-circular cut portion provided in the center via an edge on the peripheral edge of a frame coupled to a magnetic circuit. A flat speaker is formed by attaching a voice coil that fits into the magnetic gap of the magnetic circuit to this flat diaphragm. 2. The flat speaker according to claim 1, wherein the circular or non-circular cut portion penetrates the core material in the thickness direction. 3. The flat speaker according to claim 1, wherein the circular or non-circular cut portion is a part of the core material in the thickness direction. 4. The flat speaker according to claim 1, in which the circular or non-circular cut portions are discontinuous.