JPH0659117B2 - Speaker - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a speaker for HiFi reproduction in a room such as a listening room and a small hall.

2. Description of the Related Art In recent years, from the viewpoint of space saving, a wall-mounted type or a built-in type thin speaker is being developed for a speaker used in a listening room, a general household or the like. As such a thin speaker, a back open type speaker using a large-area diaphragm has long been known. However, in the case of the open rear speaker, when the sound is played close to the wall surface in the room, the out-of-phase sound from the back becomes noticeable, and the low-frequency level drops, making it difficult to reproduce powerful bass. Becomes

On the other hand, in recent years, there has been proposed a speaker that uses both a closed type speaker and a rear open type speaker. That is, it is a thin speaker in which a part of the large-area diaphragm is of a rear open type and the remaining part is of a closed type. The aim of such an eclectic speaker is to realize a required sound pressure level with a small vibration even at the time of low frequency reproduction by reducing the harmonic distortion by making the diaphragm a large area.
Compared to the case where all parts are sealed, the diaphragm makes it possible to reduce the stiffness created by the sealed space and expand the reduced playback limit, and the other parts of the diaphragm are opened and the speaker is used. By appropriately deciding the size and position of the open hole on the back side, it is possible to put a certain amount of additional mass on the diaphragm to expand the low frequency reproduction limit, and by making the path of the wraparound sound from the back side large, It is possible to reduce the influence of the reverse-phase sound to some extent.

Hereinafter, the above-described closed open eclectic type thin speaker will be described with reference to the drawings.

FIG. 2 is a front view showing the above-described conventional closed open eclectic type thin speaker. Further, FIG. 3 shows AA ′ of FIG.
FIG. In FIGS. 2 and 3, 1 is a speaker box, 2 is an edge, 3 is a diaphragm having a large area, and the diaphragm 3 is located at a closed portion 7 and a central portion by a partition wall 4 and an inner edge 11. It is divided into an open part 5 and an open part 5. Reference numeral 9 denotes a closed space formed by the closed portion 7 of the vibration plate 3, which is an element that acts as stiffness during low frequency reproduction. Reference numeral 10 denotes an open space formed by the open portion 5 of the diaphragm 3, which is located near the center of the back side of the diaphragm 3 and communicates with the outside air through an open hole 6 provided in the back surface of the speaker box 1. Further, by adjusting the opening area of the open hole 6, an appropriate additional mass is added to the open portion 5 of the diaphragm 3. Reference numeral 8 denotes a voice coil arranged at a driving position of the diaphragm 3, which is arranged at a node of natural resonance of the rectangular diaphragm 3.

In the thin speaker as described above, by adjusting the ratio between the closed system portion 7 and the open system portion 5 of the large-area diaphragm, and the opening area of the open hole 6, ₀ as a speaker system, that is, stiffness and additional mass, And the reproduction efficiency can be realized to some extent. Further, by providing the position of the open hole 6 near the center of the back surface of the speaker box 1, it is possible to lengthen the path of the wraparound sound from the back surface of the speaker box, which causes deterioration of low-frequency reproduction due to interference of antiphase sounds. Can be reduced.

FIG. 4 is a diagram showing an example in which the open portion 5 is elongated in the longitudinal direction of the diaphragm 3 in the above-described closed open eclectic type thin speaker. a is the longitudinal dimension of the diaphragm,
a'is the size of the open portion 5, and a'is set to be approximately equal to a. XX is the center line, and the open portion 5
Are arranged symmetrically with respect to XX. The principle of this conventional example is exactly the same as that of the conventional example shown in FIGS. 2 and 3 except for the difference in the shape of the open portion 5.

Problems to be Solved by the Invention However, in the configuration example shown in FIG. 2, the open portion 5 of the diaphragm 3 is located near the center of the diaphragm 3 because of the position of the opening hole 6. Therefore, when attention is paid to the longitudinal direction of the diaphragm 3, additional mass is added to the vicinity of the center, and considerably large stiffness acts on both sides of the diaphragm 3 due to the closed space, which is structurally unbalanced. Therefore, the longitudinal split resonance of the diaphragm easily occurs. Even if the voice coil 8 is located at the node of the split resonance,
It is difficult to realize perfect piston motion, and there is a problem that a flexural vibration mode is likely to occur due to uneven distribution of the reactance component and the inductance component.

In the conventional example shown in FIG. 4, since the longitudinal dimension a'of the open portion 5 is made substantially equal to the longitudinal dimension a of the diaphragm 3,
The above-mentioned inconvenience does not occur. However, the additional mass generated in the open portion 5 of the diaphragm 3 tends to be distributed in the longitudinal direction. FIG. 5 shows the result of analysis of the distribution of the additional mass along the center line XX shown in FIG. 4 by simulation by the finite element method or the like. The added mass is considerably large. Therefore, even with the structure as shown in FIG. 4, structural imbalance is likely to occur, and there is a problem that drive control for realizing complete piston motion is difficult.

In view of the above problems, the present invention provides a speaker that can reduce structural imbalance in the longitudinal direction of the diaphragm and realize good sound pressure frequency characteristics by node drive.

Means for Solving the Problems In order to solve the above-mentioned problems, the speaker of the present invention has a configuration in which the opening method portion of the diaphragm is formed substantially symmetrical with respect to the longitudinal center line along the longitudinal direction of the diaphragm. The width of the opening system portion, that is, the width in the direction orthogonal to the longitudinal direction of the diaphragm is configured such that the central portion of the diaphragm is wide and the end portion is narrow.

Action The present invention eliminates structural imbalance by making the distribution of the additional mass added to the diaphragm by the open system almost uniform in the longitudinal direction of the rectangular diaphragm most susceptible to split resonance due to the above-described configuration. It is possible to realize good piston motion over a wide band together with the vibrating plate nodal drive method.

Example Hereinafter, a speaker of an example of the present invention will be described with reference to the drawings.

FIG. 1 is a front view showing a speaker according to an embodiment of the present invention. In FIG. 1, the speaker box 1, the edge 2, the diaphragm 3, the open hole 6, the closed portion 7, and the voice coil 8 provided at the driving position of the diaphragm 3 are shown in FIGS.
It is the same as in FIG. Reference numeral 5'denotes an open portion, 4'denotes a partition wall for separating the closed portion 7 and the open portion 5 '. In the partition wall 4', the open portion 5'is the central axis X-X of the diaphragm 3.
Are arranged substantially symmetrically with respect to each other, and the width A of the end portion is smaller than the width B of the central portion.

In the speaker configured as described above, the diaphragm 3
In addition to the mass of the diaphragm 3 itself, there is an additional mass acting on the region of the open portion 5'as a mass acting on the diaphragm 3. The magnitude of this additional mass depends on the ratio of the area of the open portion 5'to the cross-sectional area of the open hole 6, that is, the transformation ratio. When this transformation ratio becomes large, the additional mass becomes a size that cannot be ignored as compared with the mass of the diaphragm 3 itself, and exerts a serious influence when the diaphragm 3 is vibrated by piston drive vibration. Assuming that the additional mass per unit area acting on the open portion 5'is m, at the time of low frequency reproduction, m is small in the central portion of the open portion 5 ', that is, in the vicinity of the open hole 6, and at the end of the open portion 5'. It will take a large value in the department. As described above, if there is a non-uniform distribution of mass in the longitudinal direction of the diaphragm 3, it becomes difficult to realize node drive, and split resonance easily occurs. In the present embodiment, the width B of the central portion of the open portion 5'where m (added mass acting per unit area, that is, the surface density of the added mass) becomes small, and the width A of the end portion where m becomes large is set to B. By making it smaller than the above, the distribution of the additional mass in the longitudinal direction of the diaphragm 3, that is, the direction along the central axis XX is made substantially uniform,
In low frequency reproduction, good piston motion of the diaphragm 3 due to node drive can be realized, and sound pressure frequency characteristics with few peak dips can be realized.

In FIG. 1, the partition wall 4 ′ is formed by a straight line from the central portion to the end portion of the diaphragm 3, but it may have a polygonal line shape or a curved shape.

Further, in FIG. 1, the number of the open holes 6 is one,
Needless to say, a plurality may be provided.

EFFECTS OF THE INVENTION According to the present invention, a part of a flat plate diaphragm having a substantially rectangular shape is arranged as an open type so that the flat plate diaphragm is arranged so as to be substantially symmetrical with respect to a center line in the longitudinal direction along the longitudinal direction of the flat plate diaphragm. ,
By forming the width of the region forming the opening method in the direction orthogonal to the longitudinal direction to be smaller than the central portion at the end portion, good piston motion of the diaphragm is realized and the peak dip is small. It is possible to provide an excellent speaker that can obtain sound pressure frequency characteristics.

[Brief description of drawings]

FIG. 1 is a front view showing a speaker in an embodiment of the present invention, FIGS. 2 and 4 are front views showing a conventional speaker, FIG. 3 is a sectional view of FIG. 2, and FIG. It is a characteristic view showing a distribution of. 1 ... speaker box, 2 ... edge, 3 ... vibration plate, 4,4 '... intermediate partition bulkhead, 5,5' ... opening part of vibration plate, 6 ... open hole, 7 ... vibration Sealing part of the plate, 8 ... Voice coil, 9 ... Sealed space, 10 ... Open space, 11 ... Inner edge.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsumasa Sato 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inst. 72) Inventor Sawako Atsugi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Shuji Saeki, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. 1006, Kadoma, Kadoma, Fuchu, Japan Matsushita Electric Industrial Co., Ltd. (56) References JP-A-63-35959 (JP, A) Actual development: Sho-60-77179 (JP, U)

Claims (1)

[Claims] 1. A flat diaphragm having a substantially rectangular shape has a structure in which a part thereof is an open system and the remaining part is a closed system, and an area constituting the open system of the flat plate is defined as an area of the flat plate diaphragm. The diaphragms are arranged along the longitudinal direction so as to be substantially symmetrical with respect to the center line in the longitudinal direction, and the region forming the open system has a width in the direction orthogonal to the longitudinal direction of the flat diaphragm. A speaker characterized in that the end portion is smaller than the center portion of the speaker.