JP4361580B2 - Speaker diaphragm and speaker - Google Patents

Description

  The present invention relates to a speaker diaphragm, and more particularly to a speaker diaphragm used for a speaker that is reduced in thickness.

  In recent years, electronic devices such as mobile phones and PDAs (personal digital assistants) have become thinner and larger screens, and have also been required to have higher sound quality. In such a situation, the speaker mounted on the electronic device is also required to be thin, slim and have high sound quality. Therefore, a slim type speaker having a shape such as a rectangle or an ellipse has been proposed (see, for example, Patent Document 1).

  FIG. 12 is a diagram showing the structure of a conventional slim type speaker. 12A is a top view of a conventional slim type speaker, and FIG. 12B is a front view of the conventional slim type speaker. In FIG. 12, the slim type speaker includes a magnet 901, a plate 902, a yoke 903, a housing 904, a cylindrical coil 905, and an elliptical (near) diaphragm 906. The diaphragm 906 has a dome-shaped portion 911 having a semi-elliptical cross section at the center (the portion inside the coil 905 fixed to the diaphragm 906). Further, the diaphragm 906 has an edge portion 912 having a semicircular cross section at an outer peripheral portion (a portion outside the dotted line in the diaphragm 906 shown in FIG. 12A). An edge portion 912 of the diaphragm 906 is supported by the housing 904. Here, the diaphragm 906 is supported so that the coil 905 is inserted into the magnetic gap between the plate 902 and the yoke 903.

In FIG. 12, since the coil 905 is circular, the driving force of the coil is difficult to propagate in the longitudinal direction of the diaphragm 906 (lateral direction in FIG. 12A). In order to prevent this, the shape of the coil may be the same elliptical shape as that of the diaphragm. Thereby, the rigidity of the diaphragm in the longitudinal direction of the coil can be maintained. However, the rigidity of the diaphragm in the direction perpendicular to the longitudinal direction cannot ensure sufficient rigidity as compared with the rigidity in the longitudinal direction. For this reason, as shown in FIG. 12, the central portion of the diaphragm is formed into a dome shape or reinforced with a voice coil bobbin or the like.
JP-A-10-191494

  However, in the conventional diaphragm structure, the diaphragm central portion needs to be formed into a dome shape or reinforced with a voice coil bobbin or the like, so that the height of the diaphragm central portion increases. Therefore, the conventional diaphragm structure has a limit in reducing the thickness of the speaker. In particular, in the case of reinforcement by a voice coil bobbin or the like, in addition to the above-described problems, there is a problem that the efficiency is lowered because the mass of the vibration system of the speaker becomes heavy.

  On the other hand, when the diaphragm is an ellipse or a rectangle, in the conventional diaphragm structure, the elasticity at the edge portion of the diaphragm is different between the vicinity of the central portion of the diaphragm and the portions that are both ends in the longitudinal direction. . Specifically, the elasticity in the vicinity of the central portion is small, and the elasticity is increased in the vicinity of both end portions. As a result, the diaphragm performs a drum movement (see FIG. 8) in which the amplitude increases as it approaches the center of the diaphragm. That is, since the entire diaphragm cannot perform the piston motion, there is a problem that the acoustic characteristics deteriorate.

  Therefore, an object of the present invention is to provide a speaker diaphragm capable of reducing the thickness of the speaker. Another object of the present invention is to provide a speaker diaphragm capable of high-quality reproduction even when the shape is an ellipse or a rectangle.

  In order to achieve the above object, the present invention has the following features. That is, the first invention is a loudspeaker diaphragm (hereinafter simply referred to as a “diaphragm”) to which a coil is fixed. The diaphragm includes an edge portion that is outside the fixed portion of the coil and a diaphragm central portion that is inside the fixed portion of the coil. A rib is provided at the center of the diaphragm.

  According to the above, the thickness of the inner portion (center portion) of the fixed portion of the coil in the diaphragm can be suppressed to the height of the rib. Therefore, the space for installing the diaphragm on the speaker can be reduced, so that the speaker can be thinned. Further, the rigidity of the central portion can be improved by the rib without making the central portion a dome shape or the like as in the prior art. As mentioned above, according to the said diaphragm, thickness reduction of a speaker can be achieved, maintaining sound quality.

  Further, when the edge portion has a portion having a convex cross-sectional shape, the rib is provided with a lower cross-sectional height than the edge portion.

  Further, when the coil has a shape extending along the first direction, the direction in which the rib is provided may include a component related to the second direction perpendicular to the first direction. Here, the “shape extending along the first direction” means that the coil has a shape in which the length in the vertical direction is different from the length in the horizontal direction, for example, a rectangle or an ellipse. That is, the “first direction” refers to the major axis direction (for example, the longitudinal direction in FIG. 1B) described later, and the “second direction” refers to the minor axis direction described later. . In this case, the ribs may be provided so as to extend in the second direction, or may be provided in a lattice shape having a predetermined angle with respect to the first direction.

  According to the above, the rib is provided in a direction perpendicular to the longitudinal direction of the coil, that is, in a direction including a component related to the second direction, thereby improving the rigidity in the second direction at the center portion of the diaphragm. Can do. Therefore, even if the planar shape of the coil is a shape having different lengths in the vertical direction and the horizontal direction, the sound quality can be maintained and the speaker can be thinned.

  Further, the rib may be provided on the side to which the coil is fixed and the height of the cross section may be lower than that of the coil. In this case, since the rib does not affect the thickness of the diaphragm at all, when designing the speaker, the designer needs to consider only the thickness of the coil and the height of the edge portion. Therefore, the speaker can be made thinner.

  Further, the rib may be provided by being molded integrally with the diaphragm central part, or may be provided by being bonded to the diaphragm central part. By forming the ribs integrally, the number of components is reduced. Furthermore, since it is not necessary to bond the diaphragm and the rib, the number of assembly steps is reduced.

  The second invention is a diaphragm to which a coil is fixed. The diaphragm includes an edge portion that is outside the fixed portion of the coil and a diaphragm central portion that is inside the fixed portion of the coil. A reinforcing portion having a flat cross section and thicker than the edge portion is provided in the central portion of the diaphragm. Note that “thicker than the edge portion” means that the thickness of the plate in the vibration center portion is larger than the thickness of the plate constituting the edge portion (not the height of the convex shape of the edge portion). .

  According to the above, like the first invention, the rigidity of the central part can be improved without making the central part a dome shape or the like. Therefore, the diaphragm according to the second invention can also reduce the thickness of the speaker while maintaining the sound quality.

  A third invention is a diaphragm having a shape extending along the first direction. Here, a coil having a shape extending along the first direction is fixed to the diaphragm. The diaphragm includes an edge portion that is outside the fixed portion of the coil and a diaphragm central portion that is inside the fixed portion of the coil. The edge portion has a shape in which the elasticity in the first direction and the elasticity in the second direction perpendicular to the first direction are substantially the same.

  According to the above, even when the planar shape of the coil is a shape in which the lengths in the vertical direction and the horizontal direction are different, the amount of vibration displacement at the central portion of the diaphragm can be suppressed. Here, in the case where the planar shape of the coil is a shape in which the lengths in the vertical direction and the horizontal direction are different, if the rib is not provided on the vibration plate, the elasticity of the portion close to the vibration plate center portion of the edge portion Is smaller than the elasticity in the vicinity of the part which becomes both ends. As a result, the vibration state of the diaphragm increases as the displacement approaches the center part of the diaphragm, and is far from the ideal piston motion. On the other hand, according to the diaphragm, for example, a rib is provided in a portion extending in the first direction in the edge portion, that is, a position close to the center of the diaphragm (see FIG. 7A described later). As a result, the elasticity of the edge portion at that position is increased, so that it is possible to balance the elasticity of the edge portion near the diaphragm center and near both ends. As a result, the vibration state of the diaphragm becomes close to the piston motion, and the sound quality can be improved.

  Further, the edge portion may be provided with a portion having a convex cross section around the fixed portion of the coil. At this time, the height of the cross section of the portion facing the first direction among the portions having a convex cross section at the edge portion is made higher than the height of the cross section of the portion facing the second direction. This can further improve the balance of elasticity of the edge portions near the diaphragm center and near both ends.

  In addition, ribs extending substantially parallel to the second direction are provided in portions of the edge portion that are located on both sides of the coil with respect to the first direction.

  In the first to third aspects of the invention, the coil may be a printed voice coil formed integrally with the speaker diaphragm. Alternatively, the shape of the diaphragm may be molded after being integrally molded with the coil by fixing the coil.

  In the first to third aspects of the invention, the edge portion may have a convex shape on the side to which the coil is fixed, at least a part of the cross-sectional shape of the portion along the outer periphery of the coil. Thus, the coil can be stably fixed to the diaphragm. Furthermore, when the coil is fixed to the diaphragm with an adhesive, the adhesive can be prevented from flowing out toward the edge portion.

  The diaphragm may be provided in a form having the features of the first invention and the features of the third invention, or a form having the features of the second invention and the features of the third invention. May be provided in The speaker diaphragm according to the first to third inventions may be provided in a form incorporated in a speaker. The speaker includes a casing that supports the diaphragm, a drive coil fixed to the diaphragm, and a magnetic circuit. The magnetic circuit may include at least two magnets arranged on both sides of the drive coil with respect to the vibration direction of the diaphragm. Further, the two magnets may be arranged such that the magnetization directions are opposite to each other with respect to the vibration direction. The diaphragm according to the first to third aspects of the present invention may be provided as an electronic device including the speaker as described above.

  According to the present invention, the rib is provided in a direction perpendicular to the longitudinal direction of the coil, that is, in a direction including a component related to the second direction, thereby improving the rigidity in the second direction at the center portion of the diaphragm. be able to. Therefore, even if the planar shape of the coil is a shape having different lengths in the vertical direction and the horizontal direction, the sound quality can be maintained and the speaker can be thinned.

(Embodiment 1)
First, a speaker diaphragm (hereinafter simply referred to as “diaphragm”) according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a diagram illustrating a structure of a speaker using the diaphragm according to the first embodiment. FIG. 2 is a diagram illustrating sound pressure frequency characteristics of a speaker using the diaphragm according to the first embodiment.

  FIG. 1A is a cross-sectional view of a speaker. In FIG. 1A, the speaker includes a first magnet 101, a second magnet 102, a coil 103, a diaphragm 104, a first housing 105, a second housing 106, One yoke 109 and a second yoke 110 are provided. The first housing 105 is provided with a first air hole 107. The second yoke 110 is provided with a second air hole 108. In the first embodiment, although the external shape of the speaker is not shown, it is assumed that the speaker is a rectangular parallelepiped having a rectangular bottom surface. Specifically, the aspect ratio of the outer shape is assumed to be 3.2 times.

  In FIG. 1A, first and second magnets 101 and 102 are rectangular parallelepiped shapes, for example, neodymium magnets having an energy product of 38 MGOe. The magnetization directions of the first and second magnets 101 and 102 are opposite directions with respect to the vibration direction of the diaphragm 104. For example, if the first magnet 101 is magnetized upward (direction from the second magnet to the first magnet), the second magnet 102 is directed downward (direction from the first magnet to the second magnet). Is magnetized. The first magnet 101 is fixed to the first yoke 109 so that the symmetry axis x passing through the centers of the first magnet 101 and the second magnet 102 coincides. Similarly, the second magnet 102 is fixed to the second yoke 110 so that the symmetry axis x coincides. The first yoke 109 is connected to the first housing 105 at the outer periphery thereof, and the second yoke 110 is connected to the second housing 106 at the outer periphery thereof. The first and second yokes 109 and 110 are made of a magnetic material such as iron. The first casings 105 and 106 are non-magnetic materials and use a resin material such as PC (polycarbonate).

  The coil 103 is formed on the diaphragm 104 so that the center thereof coincides with the first and second magnets 101 and 102, that is, the symmetry axis x is located at the center of the coil 103. In the first embodiment, the coil 103 is bonded to the diaphragm 104 with an adhesive. The diaphragm 104 is fixed by sandwiching the outer peripheral portion between the first casings 105 and 106 so that the coil 103 is located at an equal distance from the first and second magnets 101 and 102. The second air hole 108 is provided in the second yoke 110, and the first air hole 107 is provided on one surface of the first housing 105.

  FIG. 1B is a top view of diaphragm 104 and coil 103 according to the first exemplary embodiment. As shown in FIG. 1B, the diaphragm 104 has a shape extending along the vertical direction in FIG. That is, it is the shape from which the length of a vertical direction and a horizontal direction differs. Hereinafter, the longitudinal direction of the diaphragm 104 may be referred to as a major axis direction, and a direction perpendicular to the major axis direction may be referred to as a minor axis direction.

  As described above, the coil 103 is fixed to the diaphragm 104, and the coil 103 has a shape extending along the vertical direction in FIG. Specifically, the planar shape of the coil 103 is a rectangular shape. Diaphragm 104 includes an outer portion (hereinafter referred to as “edge portion”) of a fixed portion of coil 103 and an inner portion (hereinafter referred to as “center portion”) of the fixed portion of coil 103. At the edge portion, a convex portion 201 having a convex cross-sectional shape is annularly provided around a fixed portion of the coil 103 (a portion surrounded by a dotted line shown in FIG. 1B). Further, a rib 202 is provided at the center. The rib 202 is provided so as to extend in the minor axis direction of the coil 103. As a result, the rigidity in the minor axis direction at the center of the diaphragm 104 is improved.

  FIG. 1C is a cross-sectional view taken along the line AA ′ of the central portion of the diaphragm 104 shown in FIG. As shown in FIG. 1C, in the first embodiment, a plurality of ribs (13 in FIG. 1C) are provided. Each rib is provided by changing the interval of the length in the major axis direction. In the present embodiment, the depth of each rib is constant. However, you may provide each rib so that the depth for every rib may differ. Regarding the cross-section in the direction perpendicular to the direction in which the rib 202 is provided (the minor axis direction in the first embodiment), the cross-sectional shape of the rib 202 is V-shaped. The cross-sectional shape may be any shape. The central portion of the diaphragm 104 has a flat cross section other than the portion where the rib 202 is provided. That is, the central portion of the diaphragm 104 has a configuration in which a rib is integrally provided on a flat plate.

  FIG. 1D is a BB ′ cross-sectional view of the diaphragm 104 shown in FIG. As shown in FIG. 1D, the rib 202 is provided on the same side as the side on which the coil 103 is fixed and the side on which the convex portion 201 projects (projects on the same side). . The rib 202 is lower than the convex portion 201 and has a height substantially equal to that of the coil 103. Therefore, when the diaphragm 104 according to Embodiment 1 is used for a speaker, it is not necessary to consider the thickness of the central portion of the diaphragm 104 when designing the speaker. Therefore, the speaker can be made thinner than when a diaphragm having a dome shape at the center is used.

  The cross section of the convex portion 201 has a convex shape. Specifically, the convex portion 201 has a semicircular cross section, but may have another shape such as a waveform or an elliptical shape. Further, regarding the cross section in the direction in which the rib 202 is arranged (the minor axis direction in the first embodiment), the cross section of the rib 202 is trapezoidal, but may be semicircular, V-shaped, elliptical, or the like. Further, the side on which the rib 202 is provided may be the same side (the upper side in FIG. 1D) as the side on which the convex part 201 projects, or the side on which the convex part 201 projects. The reverse side (the lower side in FIG. 1D) may be used.

  The operation and effect of the speaker configured as described above will be described. With the configuration described above, a magnetic field is formed by the first and second magnets 101 and 102 and the first and second yokes 109 and 110. And the coil 103 is arrange | positioned so that the magnetic flux density may become the highest in the magnetic gap G (refer Fig.1 (a)). When an AC electrical signal is input to the coil 103, a driving force is generated. The coil 103 and the vibration plate 104 bonded thereto vibrate by the generated driving force, and sound is emitted.

  When the diaphragm 104 vibrates, the rigidity in the major axis direction of the diaphragm 104 is maintained by the coil 103. On the other hand, the rigidity of the diaphragm 104 in the minor axis direction is lower than that in the major axis direction without the rib 202 because the coil 103 has a rectangular shape. However, by providing the rib 202 in the direction of the minor axis direction, the rigidity of the diaphragm 104 in the minor axis direction is improved. As a result, since the vibration mode generated in the minor axis direction is suppressed, the reproduction limit frequency in the high range is increased.

  FIG. 2 shows sound pressure frequency characteristics when the rib 202 is provided and when the rib 202 is not provided. As shown in FIG. 2, the reproduction limit frequency in the high band when the rib 202 is provided is improved to 10 kHz, compared with the reproduction limit frequency when the rib 202 is not provided (about 4.5 kHz in FIG. 2). It is high. Thus, by providing the rib 202 at the center of the diaphragm 104, the rigidity in the minor axis direction at the center can be improved without making the center a dome shape or providing a voice coil bobbin.

  As described above, according to the first embodiment, the rigidity in the minor axis direction at the central portion of diaphragm 104 can be maintained by ribs 202. Therefore, it is possible to ensure the reproduction of the high frequency sound. Furthermore, by using the ribs 202, the thickness at the center of the diaphragm 104 can be made thinner than in the prior art. As described above, according to the first embodiment, the speaker itself can be thinned while maintaining the sound quality.

  In the first embodiment, the shape of diaphragm 104 and coil 103 is rectangular. Here, in other embodiments, the shapes of the diaphragm 104 and the coil 103 are not limited to shapes having different lengths in the vertical direction and the horizontal direction, but are shapes having the same length in the vertical direction and the horizontal direction ( For example, it may be a square). Even if the diaphragm 104 has the same length in the vertical direction and the horizontal direction, the rigidity can be increased by providing a rib at the center. In addition, the shape of the diaphragm 104 and the coil 103 may be an ellipse or the like. Further, the shapes of the diaphragm 104 and the coil 103 are not necessarily the same.

  In the first embodiment, the rigidity is improved by providing the rib 202 at the center of the diaphragm 104. Here, in another embodiment, the rigidity may be improved by increasing the thickness of the diaphragm 104. For example, only the thickness of the central portion may be increased by a technique such as uneven thickness molding or film adhesion. FIG. 2 shows sound pressure frequency characteristics when the thickness of the central portion is twice that of other portions (for example, the convex portion 201). As shown in FIG. 2, when the thickness of the central portion is twice that of other portions, the reproduction limit frequency (about 4.5 kHz) in the case where the thickness remains as it is (same as the case where the rib 202 is not provided) is obtained. In comparison, the reproduction limit frequency in the high band is improved to 7 kHz. Thus, a certain level of sound quality can be maintained even by a method in which the thickness of the central portion is made thicker than other portions. Accordingly, the sound quality can be maintained and the speaker itself can be thinned. In the case of the method of increasing the thickness of the central portion, the rigidity can be improved as the thickness is increased, but the sound pressure is reduced by increasing the weight of the diaphragm as the thickness is increased. You need to be careful.

  FIG. 3 is a diagram illustrating a cross-sectional view of the diaphragm according to the modification of the first embodiment. In the first embodiment, the height of the opening surface of the convex portion 201 and the opening surface of the rib 202 are the same (see FIG. 1D), but in the other embodiments, The heights of both need not necessarily match. In FIG. 3, a fixing rib 203 is provided along the outer periphery of the fixed portion of the coil 103. The fixing rib 203 is formed so that its cross section is convex with respect to the surface to which the coil 103 is fixed. The coil 103 can be stably fixed to the diaphragm by the fixing rib 203. Furthermore, when the coil 103 is fixed to the diaphragm with an adhesive, the adhesive can be prevented from flowing out toward the convex portion 201. The fixing rib 203 may be provided on at least a part of the portion along the outer periphery of the fixed portion of the coil 103. The cross-sectional shape of the fixing rib 203 may be a convex shape on the side to which the coil is fixed.

  In Embodiment 1, the vibration plate 104 may be formed by integrally forming the rib 202 and other portions, or the rib 202 and the vibration plate 104 may be formed separately. FIG. 4 is a diagram illustrating an example of a member including the rib 202 when the rib 202 is formed separately from the diaphragm 104. By adhering the member 204 shown in FIG. 4 to the diaphragm 104 having a flat central section, the diaphragm 104 having the rib 202 at the center can be formed.

  In Embodiment 1, the rib 202 is provided so as to extend in the minor axis direction of the diaphragm 104. However, in other embodiments, the direction in which the rib 202 is provided is not limited to this. When the planar shape of the coil is a shape in which the lengths in the vertical direction and the horizontal direction are different, the rib 202 may be provided so as to extend in a direction including a component related to the minor axis direction. This is because the rigidity in the minor axis direction can be improved. FIG. 5 is a diagram illustrating a central portion of the diaphragm 104 according to another embodiment. As shown in FIG. 5A, the rib 202 may be provided with a predetermined angle with respect to the minor axis direction (45 ° in FIG. 5A). Moreover, as shown in FIG.5 (b), you may provide in the grid | lattice form which has a predetermined angle with respect to a minor axis direction.

  FIG. 6 is a view showing a cross section of the rib 202. The inside of the rib 202 may be hollow as shown in FIG. 6 (a), or may be medium-tight (the inside is not hollow) as shown in FIG. 6 (b).

(Embodiment 2)
Hereinafter, a diaphragm according to Embodiment 2 of the present invention will be described with reference to FIGS. FIG. 7 is a diagram illustrating a diaphragm according to the second embodiment. FIG. 8 is a diagram illustrating a vibration state of the diaphragm according to the second embodiment. Although not shown, the diaphragm according to Embodiment 2 is used by being connected to a speaker, as in FIG. In the following description, the same components as those in Embodiment 1 are denoted by the same reference numerals.

  FIG. 7A is a plan view of the diaphragm according to the second embodiment. As shown in FIG. 7A, the diaphragm 301 has a shape extending along the vertical direction in FIG. In other words, like the diaphragm 104, the lengths in the vertical direction and the horizontal direction are different.

  The diaphragm 301 is different from the diaphragm 104 in that a rib 303 is provided on the convex portion 302. As shown in FIG. 7A, the rib 303 is provided in a portion of the convex portion 302 that faces the major axis direction (vertical direction in FIG. 7A). The rib 303 is provided so as to extend in the minor axis direction (lateral direction in FIG. 7A). Other configurations such as the central portion of the diaphragm 301 are the same as those of the diaphragm 104.

  FIG. 7B is a cross-sectional view taken along the line CC ′ of the diaphragm 301 shown in FIG. FIG. 7B shows only a portion where the rib 303 is provided. As shown in FIG. 7 (b), in the second embodiment, a plurality of (11 in FIG. 7 (b)) ribs are provided. Each rib is provided by changing the interval of the length in the major axis direction. The depth of each rib is constant. 7B, the cross-sectional shape of the rib 303 is V-shaped, but the cross-sectional shape may be any shape.

  FIG. 7C is a DD ′ cross-sectional view of the diaphragm 104 shown in FIG. The dotted line portion of the semi-elliptical curve shown in FIG. 7C shows the surface of the convex portion 302. On the other hand, the straight line that is the chord of the dotted line portion indicates the V-shaped tip of the rib 303. That is, the rib 303 is provided so as to have a certain depth from the apex in the cross section of the convex portion 302 having a semi-elliptical shape. FIG. 7C is the same as FIG. 1D except that ribs 303 are provided.

  As described above, by providing the rib 303 on the convex portion 302, the elasticity of the convex portion 302 can be changed. Specifically, by providing the rib 303 in the convex portion 302 in the portion near the center of the diaphragm 301, the elasticity of the portion can be increased.

  FIG. 8 is a diagram showing a vibration state in the major axis direction of the diaphragm when radiating 250 Hz sound. 8 has the same structure as that of the diaphragm 301 except that the vibration state of the diaphragm 301 provided with ribs 303 on the convex part 302 (“with ribs” in FIG. 8) and that the ribs are not provided on the convex part. A vibration state of a certain diaphragm (“no rib” in FIG. 8) is shown.

  As shown in FIG. 8, for the diaphragm without the ribs on the convex portion, the difference between the deformation amount near the center of the diaphragm and the deformation amount at both ends (both ends in the major axis direction) is large. This is because the ribs are not provided on the convex part, so the elasticity of the convex part near the center of the diaphragm and the elasticity of the convex part far from the center of the diaphragm are not balanced. It is. In other words, near the center of the diaphragm, the amount of deformation increases because the elasticity of the convex portion is small, whereas at both ends of the diaphragm, the amount of deformation decreases because of the elasticity of the convex portion. . For this reason, the diaphragm becomes a vibration state far from the ideal piston motion, and when the diaphragm vibrates, a vibration mode that adversely affects the acoustic characteristics occurs.

  In contrast, for the diaphragm 301, the difference between the deformation amount near the center of the diaphragm and the deformation amount at both ends is small. This is because the rib 303 is provided on the convex portion 302, thereby improving the balance between the elasticity of the convex portion near the center of the diaphragm and the elasticity of the convex portion far from the center of the diaphragm. This is because the. That is, the deformation amount is suppressed by increasing the elasticity of the convex portion 302 by the rib 303 near the center of the diaphragm. As a result, the entire vibration plate 301 vibrates close to the piston motion, and the acoustic characteristics can be improved.

  As described above, according to the second embodiment, by providing ribs on the convex portion, even when the diaphragm has a shape with different lengths in the vertical direction and the horizontal direction, the balance of elasticity of the convex portion is obtained. Can be taken. Therefore, the sound quality can be improved. Further, as shown in FIG. 8, since the amount of displacement at the central portion of the diaphragm can be suppressed, other members of the speaker (for example, the first and second magnets 101 and 102 shown in FIG. 1 (a)). ) Can be placed closer to the diaphragm. That is, the speaker can be thinned.

  In the second embodiment, the rib 202 is provided at the center of the diaphragm, but the rib 202 may not be provided. Even in that case, the effect of the rib 303 is the same as described above.

  Moreover, in the modification of Embodiment 2, the structure which further provides a tangential rib in the convex part 302 may be sufficient. FIG. 9 is a plan view of a diaphragm according to a modification of the second embodiment. As shown in FIG. 9, the tangential rib 304 is provided in a portion of the convex portion 302 that is near both ends in the major axis direction. A plurality of tangential ribs 304 are provided, and the extending directions thereof are different. As described above, by providing the tangential rib 304 in the convex portion 302 at a portion far from the center of the diaphragm 301, the elasticity of the portion can be reduced. Thereby, the balance of elasticity of the convex portion 302 can be further improved. As described above, in another embodiment, the elasticity of the entire convex portion 302 may be adjusted by adding a tangential rib in addition to the rib.

  In the second embodiment, the height of the cross section of the convex portion 302 is the same in any portion, but the elasticity of the convex portion 302 may be adjusted by changing the height of the cross section. Specifically, in the convex portion 302, the height of the portion near the center of the diaphragm is increased, and the height of the portion far from the center of the diaphragm is decreased. Also by this method, the elasticity of the convex portion 302 can be adjusted.

  Further, in the second embodiment, as in the first embodiment, a configuration in which a fixing rib is provided may be used (see FIG. 3). By providing the fixing rib, the coil can be stably fixed to the diaphragm as in the first embodiment. Furthermore, when the coil is fixed to the diaphragm with an adhesive, the adhesive can be prevented from flowing out toward the convex portion.

  In the first and second embodiments, a wound coil is used as the coil 103. However, in other embodiments, for example, a diaphragm (for example, polyimide) is plated with copper and etched to form a diaphragm. You may use the printed coil printed on. Further, the shape of the coil 103 may be elliptical.

  In the first and second embodiments, diaphragm 104 and coil 103 are created by a method in which coil 103 is later adhered to diaphragm 104 in which ribs are integrally formed. Here, the method of creating the diaphragm 104 and the coil 103 may be a method of forming the diaphragm 104 after the coil 103 is bonded to the diaphragm 104. In particular, when the above-described printed coil is used, this method is preferable. In the first and second embodiments, the coil 103 is bonded to one side of the diaphragm 104, but the coil may be bonded to both sides of the diaphragm 104.

  Further, as a material of the diaphragm according to the first or second embodiment, for example, a material such as paper or PEN (polyethylene naphthalate) other than PEI (polyetherimide) may be considered in accordance with target characteristics.

  In the first and second embodiments, the edge portion is provided with the convex portion, but may be configured without the convex portion. That is, the cross section of the edge portion may be flat. At this time, the rib 303 in the second embodiment is provided at the same position as in the case where the convex portion is present.

  In Embodiments 1 and 2, the example in which the diaphragm according to the present invention is used for a speaker of a type in which two magnets are sandwiched has been described. However, other types of magnetic circuits and driving systems such as an inner magnet type and an outer magnet type are described. The diaphragm according to the present invention can also be used in a speaker of the type. Furthermore, since the speaker using the diaphragm according to the present invention can be easily reduced in thickness, it is effective to use it for electronic devices such as mobile phones and PDAs.

  A mobile phone which is an example of an electronic device including the speaker using the diaphragm described in Embodiment 1 or 2 will be described. FIG. 10 is a partially cutaway view of the mobile phone, and FIG. 11 is a block diagram showing a schematic configuration of the mobile phone.

  In FIG. 10, a mobile phone 401 includes a housing 402 of the mobile phone 401, a sound hole 403 provided in the housing 402, and a speaker 404 using the diaphragm described in Embodiment 1 or 2. Yes. The diaphragm of the speaker 404 is provided so as to face the sound hole 403 inside the housing 402.

  In FIG. 11, a cellular phone 401 includes an antenna 501, a transmission / reception circuit 502, a calling signal generation circuit 503, a speaker 404, and a microphone 505. The transmission / reception circuit 502 includes a demodulation unit 5021, a modulation unit 5022, a signal switching unit 5023, and an absence recording unit 5024.

  The antenna 501 receives radio waves output from the nearest base station. Demodulation section 5021 decodes the modulated wave input from antenna 501 and converts it into a received signal, and provides the received signal to signal switching section 5023. The signal switching unit 5023 is a circuit that switches signal processing according to the content of the received signal. That is, when the received signal is a call signal, the received signal is given to the call signal generating circuit 503, when the received signal is a voice signal, the received signal is given to the speaker 404, and when the received signal is a voice signal of absence recording, The received signal is given to the absence recording unit 5024. The absence recording unit 5024 is composed of, for example, a semiconductor memory. The absence recording message when the power is turned on is stored in the absence recording unit 5024. However, when the mobile phone is outside the service area or when the power is off, the absence recording message is stored in the storage device of the base station. A call signal generation circuit 503 generates a call signal and supplies it to the speaker 404.

  Similar to a conventional mobile phone, a small microphone 505 is provided. The modulation unit 5022 is a circuit that modulates a dial signal or an audio signal converted by the microphone 505 and outputs the modulated signal to the antenna 501.

  The operation of the mobile terminal device having such a configuration will be described. The radio wave output from the base station is received by the antenna 501 and demodulated into a baseband received signal by the demodulator 5021. When the signal switching circuit 5023 detects the calling signal from the incoming signal, the signal switching circuit 5023 outputs the incoming signal to the calling signal generation circuit 503 in order to notify the user of the mobile phone of the incoming call.

  Upon receiving such an incoming signal, the call signal generation circuit 503 outputs a call signal that is a pure tone in the audible band or a composite tone signal thereof. The user knows the incoming call by listening to the ringing tone output from the speaker 404 through the sound hole 403 provided in the mobile phone.

  When the user enters the receiving state, the signal switching unit 5023 adjusts the level of the received signal and then directly outputs the audio signal to the speaker 404. The speaker 404 operates as a receiver or a speaker and reproduces an audio signal.

  The user's voice is picked up by the microphone 505 and input to the modulation unit 5022 converted into an electric signal. The audio signal is modulated, converted into a predetermined carrier wave, and output from the antenna 501.

  Further, when the user of the cellular phone turns on the power and sets it to the absence recording state, the transmitted content is stored in the absence recording unit 5024. When the user of the portable terminal is turned off, the transmitted content is temporarily stored in the base station. When the user makes a request to reproduce the absence recording by key operation, the signal switching unit 5023 receives this request and acquires a recording message from the absence recording unit 5024 or the base station. The signal switching unit 5023 adjusts the acquired audio signal to the loudness level and outputs it to the speaker 404. At this time, the speaker 404 operates as a receiver or a speaker and outputs a message.

  In the above application example, the speaker is directly attached to the housing, but may be attached on a substrate built in the mobile phone. Moreover, the same operation and effect can be obtained even if it is attached to another electronic device.

The figure which shows the structure of the speaker using the diaphragm which concerns on Embodiment 1. FIG. The figure which shows the sound pressure frequency characteristic of the speaker using the diaphragm which concerns on Embodiment 1. FIG. It is a figure which shows sectional drawing of the diaphragm in other embodiment. The figure which shows an example of the member containing the rib 202 in the case of shape | molding the rib 202 separately from the diaphragm 104. The figure which shows the center part of the diaphragm 104 in other embodiment. The figure which shows the cross section of the rib 202 The figure which shows the diaphragm which concerns on Embodiment 2. FIG. The figure which shows the vibration mode of the diaphragm which concerns on Embodiment 2. FIG. The top view of the diaphragm in other embodiments Partially broken view of a cellular phone provided with a speaker using the diaphragm shown in Embodiment 1 or 2 FIG. 3 is a block diagram illustrating a schematic configuration of a mobile phone including a speaker using the diaphragm described in Embodiment 1 or 2. The figure which shows the structure of the conventional slim type speaker

Explanation of symbols

103 Coil 104, 301 Diaphragm 201, 302 Convex part 202 Rib 303 Rib

Claims (8)

A speaker comprising an elongated flat diaphragm for a speaker to which one coil is fixed,
The elongated speaker diaphragm is:
An edge portion that is outside the fixed portion of the coil;
A diaphragm central portion that is inside the fixed portion of the coil,
In the diaphragm central portion, a plurality of ribs are provided on the side to which the coil is fixed, integrally with the diaphragm central portion so that the height of the cross section is lower than the coil,
The coil has a shape extending along a first direction which is a longitudinal direction of the diaphragm,
The rib is provided in a second direction substantially perpendicular to the first direction, the cross-sectional shape is convex with respect to the surface on which the coil is fixed, and the inside of the cross section is hollow.
The speaker includes a casing that supports the elongated speaker flat diaphragm, and a magnetic circuit.
The magnetic circuit includes a magnet arranged with the coil interposed therebetween, and a magnetic circuit is constituted by a yoke coupled to the magnet, and the one coil is made to vibrate the elongated flat plate diaphragm for a speaker. A speaker that is arranged near two gaps provided in the same direction as the direction, as seen from the cross-sectional direction in the second direction, and causes the magnetic flux generated in the gap to act on the coil.   The speaker according to claim 1, wherein the edge portion of the elongated speaker diaphragm has a portion having a convex cross-sectional shape.   The speaker according to claim 1, wherein the rib of the elongated speaker diaphragm is provided by being bonded to a central portion of the diaphragm.   Of the edge portion of the elongated speaker diaphragm, ribs extending substantially parallel to the second direction are provided in portions located on both sides of the second direction with respect to the coil. The speaker according to claim 1, wherein: The edge portion of the elongated speaker diaphragm is provided with an annular portion having a convex cross section around the fixed portion of the coil,
The height of the cross section of the portion facing the first direction among the portions having a convex cross section at the edge portion is higher than the height of the cross section of the portion facing the second direction. The speaker according to any one of the above.   6. The speaker according to claim 1, wherein the coil of the elongated speaker diaphragm is a printed voice coil formed integrally with the speaker diaphragm. 7.   The speaker according to claim 1, wherein the elongated speaker diaphragm is molded integrally with the coil by fixing the coil, and then the shape is molded.   The edge portion of the elongated speaker diaphragm protrudes on the surface side where the coil is fixed to the diaphragm at least at a part of the edge portion along the outer periphery of the coil. The speaker according to any one of claims 1 to 3, wherein a fixing rib as a mold is provided.

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