JPS61139191A - Plane speaker - Google Patents

Abstract

PURPOSE:To remove a peak in a zone of a high tone of a plane speaker without increasing a distorsion and lowering a reproducing zone by forming a cutting groove of a circular shape at a center portion of a core member of a plane disphragm and providing a voice coil having an outer diameter substantially the same as the circle. CONSTITUTION:A plane diaphragm 14 is constructed by cutting once a center section 14b of a core member 14a of a honey-comb structure by using a punching die, fitting the cut center section 14b of the core member 14a into an original position, and bonding aluminum skin materials 14c, 14d to upper and lower sections of the core material 14a. A voice coil 15 has an outer diameter substantially equal to the cut diameter of the center portion 14b of the plane diaphragm 14 and bonded to a diaphragm 9 by a bonding agent such as urethane bonding agent. At a cetner por- tion and in the vicinity of the plane diaphragm, a suitable compliance is applied and a separate oscillation at this portion is controlled, an oscillation loss at the center portion is decreased, and the distorsion can be restricted.

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.

Prior Art As shown in Fig. 4, a conventional flat speaker consists of a plate (2) having a center ball (1), a ring-shaped magnet (3), and a ring-shaped plate (4) stacked together. A frame (6) is placed on the magnetic circuit (5) configured by
), attach an edge (8) such as a free edge together with a gasket (7) to the peripheral edge of this frame (6), connect the peripheral edge of a flat diaphragm (9) to this edge (8), and Drive cone (
10), and a voice coil (12) that fits into the magnetic gap (11) of the magnetic circuit (5) is connected to the center of the drive cone (10).

This voice coil (12) was held by a damper (13).

Problems to be Solved by the Invention In such conventional planar speakers, 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 center 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. The sound pressure frequency characteristics of this conventional flat speaker are shown in FIG. 5 by a solid line (a), and the second-order distortion is shown by a solid line (C).

The sound pressure frequency characteristics of a flat speaker using a relatively soft material with high internal loss as the skin material and drive cone of the flat diaphragm are shown in No. 5 by the dashed line (b),
Further, the second-order strain is shown by a broken line (d). In this configuration,
Although the peak in the treble range has been removed, 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 is also a structure in which the central part of the plane diaphragm is cut out and filled with a different material that has a large internal loss, but this structure reduces the appearance quality, increases the cost due to the increase in man-hours in the manufacturing process of the plane diaphragm, and prevents plane vibrations. There were problems such as a decrease in the high frequency reproduction frequency band due to a decrease in surface rigidity at the center of the plate.

An object of the present invention is to provide a flat speaker that solves the above problems.

Means for Solving the Problems In order to solve the above problems, the flat speaker of the present invention includes a flat diaphragm made by pasting skin materials on both sides of a core material with a circular cut groove formed in the center, and a magnetic a frame coupled to the groove, an edge connecting the peripheral edge of the frame and the peripheral edge of the planar diaphragm, and an edge having substantially the same outer diameter as a circle formed by the cut groove of the core material and the flat surface; The voice coil is coupled to the diaphragm and fitted into the magnetic gap of the magnetic circuit.

Embodiment One embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 2 is a cross-sectional view of a flat speaker according to an embodiment of the present invention, and the same components as those shown in FIG. 4 are given the same reference numerals and their explanations will be omitted. In the second pl, (14) is a plane diaphragm, and this plane diaphragm (14)
As shown in the first [il], the honeycomb structure core material (
The center part (14b) of the core material (14a) is cut once using a cutting die, and then the center part (14b) of the cut core material (14a) is cut.
b) is inserted into the original position, and aluminum skin materials (14e) (14d) are attached to the top and bottom of this core material (14a). Further, (15) is a voice coil, which has an outer diameter approximately equal to the cut diameter of the center part (14b) of the flat diaphragm (14), and is attached to the flat diaphragm (9) with urethane adhesive. ing.

The cutting diameter of the center part (14b) of the plane diaphragm (14) and the outer diameter of the voice coil (15) are 1°.
4) 15% to 35% of the outside diameter' or outside diameter dimension
There was a significant effect when the amount was within the range of . This is done by cutting the center part (14b) of the flat diaphragm (14).

This is because an appropriate amount of compliance is given near the center of the sound axis, and this compliance causes reverse resonance that cancels out the abnormal resonance at the center in the high frequency range. In addition, the weight of the flat diaphragm (14) and the core material (14a) are placed in the center.
), which causes a loss in the amplitude of the flat diaphragm (14) of the flat speaker, and the split vibration of this part is suppressed. . In addition, a voice coil (I) with approximately the same diameter as the cutting part
By driving the center part in step 5), vibration loss in the center part can be reduced and distortion can be suppressed.

The sound pressure frequency characteristics and second-order distortion of this flat speaker are shown in Figure 3.Compared to the conventional flat speaker shown in Figure 5, the peak in the treble range is significantly lower, and the overall treble range is The sound pressure level has not decreased, and the frequency response is flat with little distortion.

Effects of the Invention As described above, according to the present invention, the high frequency peak of a flat speaker can be removed with a simple configuration without lowering the reproduction band of the flat speaker or increasing distortion, thereby improving the sound quality. It is possible to flatten the pressure frequency characteristics, and the appearance quality does not deteriorate, so its industrial utility value is extremely large.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of a flat diaphragm of a flat speaker according to an embodiment of the present invention, FIG. 2 is a sectional view of the flat speaker, and FIG. 3 is a sound pressure frequency characteristic and second-order distortion of the flat speaker. FIG. 4 is a sectional view of a conventional flat speaker, and FIG. 5 is a characteristic diagram showing sound pressure frequency characteristics and second-order distortion of the conventional flat speaker. (5)... Magnetic circuit, (6)... Frame, (8
)...Edge, (11)...Magnetic gap, (14
)...Plane diaphragm, (14a)...Core material, (14
b)...Central part, (14c) (14d)...Aluminum skin material agent Yoshihiro MorimotoFigure 1Figure 2

Claims (1)

[Claims] 1. A planar diaphragm made of a core material with a circular cut groove formed in the center and skin materials attached to both sides, a frame coupled to a magnetic circuit, and a peripheral portion of this frame and the planar diaphragm. a voice coil that has approximately the same outer diameter as the circle formed by the cut groove of the core material, is coupled to the planar diaphragm, and fits into the magnetic gap of the magnetic circuit; Equipped with a flat speaker.