WO2008030026A1

WO2008030026A1 - Diaphragm for sound converter and sound converter

Info

Publication number: WO2008030026A1
Application number: PCT/KR2007/004257
Authority: WO
Inventors: Seung-Kiu Jeong; Cheon-Myeong Kim
Original assignee: Em-Tech. Co., Ltd.
Priority date: 2006-09-04
Filing date: 2007-09-04
Publication date: 2008-03-13
Also published as: KR100788476B1

Abstract

The present invention discloses a diaphragm for a sound converter and a sound converter used for a mobile communication terminal and an equivalent sound apparatus thereof, and particularly, a sound converter provided with a diaphragm including two or more layers made of different materials. The diaphragm for the sound converter includes a first vibration member layer composed of a side dome portion on an edge side and a center dome portion on a center side, and a second vibration member layer attached to the first vibration member layer, and made of a material with higher elasticity than that of the first vibration member layer.

Description

DIAPHRAGM FOR SOUND CONVERTER AND SOUND

CONVERTER

Technical Field

[1] The present invention relates to a diaphragm for a sound converter and a sound converter used for a mobile communication terminal and an equivalent sound apparatus, and more particularly, to a sound converter provided with a diaphragm including two or more layers made of different materials.

[2]

Background Art

[3] Fig. 1 is a cross-sectional view illustrating a conventional speaker and diaphragm.

In the conventional microspeaker, a yoke 2 is attached to a frame 7, a magnet 3 is attached onto the yoke 2, a top plate 4 is attached onto the magnet 3, a voice coil 5 is attached to an isolation space 1 defined by the yoke 2, the magnet 3 and the top plate 4, and a protector 8 are attached to the frame 7 to secure a diaphragm 6 and a vibration space.

[4] Normally, the diaphragm 6 used in the conventional microspeaker is molded with a single polyethylene (PE) or polypropylene (PP) based film. The PE or PP based film has a weak elastic force and a strong rigidity. If a thick film is used to satisfy a sound characteristic of a middle or high frequency band, it improves the sound characteristic of the middle or high frequency band, but deteriorates a sound pressure level (SPL) and a sound characteristic of a low frequency band. If a thin film is used to satisfy the sound characteristic of the low frequency band, since a displacement of the low frequency band increases, a sound pressure level of the low frequency band rises. However, a split vibration occurs in a specific frequency band due to the small thickness. Further, as a fast response to an input signal, namely, a dynamic characteristic is not obtainable, a total harmonic distortion (THD) is worsened. Moreover, as the conventional microspeaker adjusts the sound characteristic merely by the shape and thickness of the diaphragm molded with the single PE or PP based film, there is a limit in the improvement of the sound characteristic.

[5]

Disclosure of Invention

Technical Problem

[6] An object of the present invention is to provide a diaphragm for a sound converter and a sound converter which can improve not only a sound characteristic of a low frequency band but also a sound characteristic of a middle or high frequency band by changing a material of the diaphragm and remedying a defect thereof, and particularly, to provide a sound converter which can improve a sound characteristic, by including a diaphragm capable of improving not only a sound characteristic of a low frequency band but also a sound characteristic of a middle or high frequency band.

[7]

Technical Solution

[8] In order to achieve the above-described object, there is provided a diaphragm for a sound converter, including: a first vibration member layer composed of a side dome portion on an edge side and a center dome portion on a center side; and a second vibration member layer attached to the first vibration member layer, and made of a material with higher elasticity than that of the first vibration member layer.

[9] Preferably, the second vibration member layer is attached merely to the side dome portion of the first vibration member layer.

[10] Preferably, the diaphragm further includes a third vibration member layer attached to the side dome portion of the first vibration member layer and the second vibration member layer, and made of the same material as that of the first vibration member layer.

[11] Preferably, the diaphragm further includes a third vibration member layer attached to the opposite face to the face of the second vibration member layer to which the first vibration member layer is attached, and made of the same material as that of the first vibration member layer.

[12] Preferably, the first vibration member layer is made of polyethylene or polypropylene, and the second vibration member layer is made of thermoplastic polyurethane.

[13] Preferably, the first vibration member layer to the third vibration member layer are welded by heat and pressure.

[14] In addition, there is provided a sound converter including an isolation space defined by a frame, a yoke, a magnet and a top plate, a diaphragm and a voice coil, wherein the diaphragm includes a first vibration member layer composed of a side dome portion and a center dome portion; and a second vibration member layer attached to the first vibration member layer, and made of a material with higher elasticity than that of the first vibration member layer.

[15] Preferably, the second vibration member layer of the diaphragm for the sound converter is attached merely to the side dome portion of the first vibration member layer.

[16] Preferably, the diaphragm for the sound converter further includes a third vibration member layer attached to the side dome portion of the first vibration member layer and the second vibration member layer, and made of the same material as that of the first vibration member layer. [17] Preferably, the diaphragm for the sound converter further includes a third vibration member layer attached to the center dome portion of the second vibration member layer in an opposite direction to an attachment direction of the first vibration member layer, and made of the same material as that of the first vibration member layer. [18] Preferably, the first vibration member layer of the diaphragm is welded to the voice coil in an opposite direction to an attachment direction to the second vibration member layer of the diaphragm. [19] Preferably, the first vibration member layer to the third vibration member layer of the diaphragm are welded by heat and pressure. [20] Preferably, the first vibration member layer is made of polyethylene or poly propylene, and the second vibration member layer is made of thermoplastic polyurethane.

Advantageous Effects

[21] In this configuration, the sound converter improves not only the sound characteristic of the low frequency band but also the sound characteristic of the middle or high frequency band by changing the material of the diaphragm and remedying the defect thereof. Particularly, the sound converter improves the sound characteristic, by including the diaphragm capable of improving not only the sound characteristic of the low frequency band but also the sound characteristic of the middle or high frequency band.

[22]

Brief Description of the Drawings

[23] Fig. 1 is a cross-sectional view illustrating a conventional speaker and diaphragm;

[24] Figs. 2 and 3 are views illustrating first and second embodiments of a diaphragm for a sound converter according to the present invention, and states where the diaphragms are attached to speakers;

[25] Figs. 4 and 5 are views illustrating third and fourth embodiments of the diaphragm for the sound converter according to the present invention;

[26] Figs. 6 to 8 are explanatory views respectively illustrating methods of manufacturing diaphragms for sound converters according to the present invention; and

[27] Figs. 9 and 10 are graphs showing effects of the sound converter according to the present invention.

[28]

Best Mode for Carrying Out the Invention

[29] Figs. 2 and 3 are views illustrating first and second embodiments of a diaphragm for a sound converter according to the present invention, and states where the diaphragms are attached to speakers. Fig. 2 shows the first embodiment of the diaphragm for the sound converter according to the present invention. While a yoke 2, a magnet 3, a top plate 4, a frame 7 and an isolation space 1 are identical to those of Fig. 1, a structure of a diaphragm 6 is improved. The diaphragm 6 includes a polyethylene (PE) or polypropylene (PP) based film 21, and a thermoplastic polyure thane (TPU) 20 attached thereto. According to the present invention, the diaphragm 6 is composed of the general PE or PP based film with a weak elastic force and the TPU with a strong elastic force and a weak chemical resistance, to improve sound quality in a middle or high frequency band as well as a low frequency band. The sound quality improvement of the sound converter using the diaphragm will later be explained.

[30] Fig. 3 shows the second embodiment of the diaphragm for the sound converter according to the present invention. The second embodiment of the diaphragm 6 is identical to the first embodiment of the diaphragm of Fig. 2 in that it includes a PE or PP based film 21 and a TPU 20 attached thereto. However, in the second embodiment, the TPU 20 is attached merely to the side dome portion of the PE or PP based film 21 of the diaphragm 6. In this diaphragm 6, the elasticity of the side dome portion is different from the elasticity of the center dome portion. It is thus possible to separately control a sound characteristic of a low frequency band influenced by the side dome and a sound characteristic of a middle or high frequency band influenced by the center dome. The right sides of Figs. 2 and 3 illustrate the sound converters attached with the diaphragms, respectively, as seen from the front.

[31] Figs. 4 and 5 are views illustrating third and fourth embodiments of the diaphragm for the sound converter according to the present invention. Fig. 4 shows the third embodiment of the diaphragm for the sound converter according to the present invention. In the third embodiment, a PE or PP based center dome portion film 23 is attached onto a PE or PP based film 21 of a diaphragm 6, and a TPU 20 is attached to the side dome portion of the PE or PP based film 21 and the PE or PP based center dome portion film 23. Like the second embodiment, in this diaphragm 6, the elasticity of the side dome portion is different from the elasticity of the center dome portion. It is thus possible to separately control a sound characteristic of a low frequency band influenced by the side dome and a sound characteristic of a middle or high frequency band influenced by the center dome.

[32] Fig. 5 shows the fourth embodiment of the diaphragm for the sound converter according to the present invention. In the fourth embodiment, a TPU 20 is attached onto a PE or PP based film 21 of a diaphragm 6, and a PE or PP based center dome portion film 23 is additionally attached to the center dome portion of the TPU 20. In this diaphragm 6, the elasticity of the side dome portion is different from the elasticity of the center dome portion. It is thus possible to separately control a sound characteristic of a low frequency band influenced by the side dome and a sound characteristic of a middle or high frequency band influenced by the center dome.

[33] In the second to fourth embodiments of the diaphragm for the sound converter, the rigidity of the side dome is different from the rigidity of the center dome. In the prior art, as the diaphragm is made of a single material, it is difficult to make the rigidity of the side dome and the rigidity of the center dome different. Therefore, if the rigidity of the whole diaphragm is increased to improve the sound characteristic of the middle or high frequency band, the sound characteristic of the low frequency band is deteriorated. Conversely, if the rigidity of the whole diaphragm is decreased to improve the sound characteristic of the low frequency band, the sound characteristic of the middle or high frequency band is deteriorated. However, in the second to fourth embodiments of the diaphragm, the rigidity of the side dome can be adjusted to improve the sound characteristic of the low frequency band, and the rigidity of the center dome can be adjusted to improve the sound characteristic of the middle or high frequency band. Such adjustments can be made by changing the thickness of the PE or PP based film and the thickness of the TPU, respectively. In the above configuration, the diaphragm can improve the sound characteristics of the low frequency band and the middle or high frequency band at the same time.

[34] Figs. 6 to 8 are explanatory views respectively illustrating methods of manufacturing diaphragms for sound converters according to the present invention. Fig. 6 is an explanatory view illustrating a method of manufacturing the first embodiment of the diaphragm for the sound converter. A PE or PP film 21 is seated on a top face of a diaphragm mold 32, and a TPU 20 is seated thereon. The PE or PP film 21 and the TPU 20 are fixed by a hood 30. As heat is generated at the bottom end of the diaphragm mold 32 and pressure is generated inside the hood 30, the two materials are welded into a diaphragm.

[35] Fig. 7 is an explanatory view illustrating a method of manufacturing the second embodiment of the diaphragm for the sound converter. In detail, the top left side is an explanatory view illustrating a method of manufacturing a TPU 20', the top right side is an explanatory view illustrating a method of manufacturing a PE or PP film 21', and the bottom side is an explanatory view illustrating a method of welding the TPU 20' and the PE or PP film 21'. The methods of molding the TPU 20' and the PE or PP film 21' are identical to that of Fig. 6. However, as the TPU 20' and the PE or PP film 21' are separately molded, a welding process is not needed. In the case of the TPU 20', a process of cutting a center dome portion of the diaphragm is necessary. As explained with reference to Fig. 6, the PE or PP film 21' and the TPU 20' are fixed by a hood 30, heat is generated at a bottom end of a diaphragm mold 32, and pressure is generated inside the hood 30, so that the two molded portions are welded.

[36] Fig. 8 is an explanatory view illustrating methods of manufacturing the third and fourth embodiments of the diaphragm for the sound converter. In detail, the left side is an explanatory view illustrating a method of manufacturing the third embodiment of the diaphragm for the sound converter, and the right side is an explanatory view illustrating a method of manufacturing the fourth embodiment of the diaphragm for the sound converter. A TPU 20, a PE or PP film 21 and a PE or PP based center dome portion film 23 are seated on a top end of a diaphragm mold 32 to overlap with each other, and fixed by a hood 30. Heat is generated at the bottom end of the diaphragm mold 32 and pressure is generated inside the hood 30, so that the TPU 20, the PE or PP film 21 and the PE or PP based center dome portion film 23 are welded.

[37] Figs. 9 and 10 are graphs showing effects of the sound converter according to the present invention. Fig. 9 is a graph showing an SPL characteristic of the sound converter according to the present invention. As compared with an SPL characteristic (dotted line) of the sound converter using the general diaphragm, the SPL characteristic of the sound converter according to the present invention is less bent by frequencies. The less dB is varied by frequencies, the better the SPL characteristic is. It is thus recognized that the sound characteristic has been improved.

[38] Fig. 10 is a graph showing a THD characteristic of the sound converter according to the present invention. A THD value is wholly reduced. Particularly, the THD value is remarkably reduced at a frequency showing a high THD in the conventional mi- crospeaker. The smaller the THD value is, the more the sound characteristic is improved. As a result, the sound characteristic has been improved in the whole frequency bands.

[39]

Industrial Applicability

[40] The sound converter using the diaphragm formed of two or more materials can improve the sound characteristic in the whole frequency bands. The present invention provides the sound converter which improves the sound characteristic by including the diaphragm capable of improving not only the sound characteristic of the low frequency band but also the sound characteristic of the middle or high frequency band.

[41] Although the preferred embodiments of the present invention have been described, it is understood that the present invention should not be limited to these preferred embodiments but various changes and modifications can be made by one skilled in the art within the spirit and scope of the present invention as hereinafter claimed.

[42]

Claims

[1] A diaphragm for a sound converter, comprising: a first vibration member layer composed of a side dome portion on an edge side and a center dome portion on a center side; and a second vibration member layer attached to the first vibration member layer, and made of a material with higher elasticity than that of the first vibration member layer.

[2] The diaphragm for the sound converter of claim 1, wherein the second vibration member layer is attached merely to the side dome portion of the first vibration member layer.

[3] The diaphragm for the sound converter of claim 1, further comprising a third vibration member layer attached to the side dome portion of the first vibration member layer and the second vibration member layer, and made of the same material as that of the first vibration member layer.

[4] The diaphragm for the sound converter of claim 1, further comprising a third vibration member layer attached to the opposite face to the face of the second vibration member layer to which the first vibration member layer is attached, and made of the same material as that of the first vibration member layer.

[5] The diaphragm for the sound converter of any one of claims 1 to 4, wherein the first vibration member layer is made of polyethylene or polypropylene, and the second vibration member layer is made of thermoplastic polyurethane.

[6] The diaphragm for the sound converter of any one of claims 1 to 4, wherein the first vibration member layer to the third vibration member layer are welded by heat and pressure.

[7] A sound converter comprising an isolation space defined by a frame, a yoke, a magnet and a top plate, a diaphragm and a voice coil, wherein the diaphragm comprises a first vibration member layer composed of a side dome portion and a center dome portion; and a second vibration member layer attached to the first vibration member layer, and made of a material with higher elasticity than that of the first vibration member layer.

[8] The sound converter of claim 7, wherein the second vibration member layer of the diaphragm for the sound converter is attached merely to the side dome portion of the first vibration member layer.

[9] The sound converter of claim 7, wherein the diaphragm for the sound converter further comprises a third vibration member layer attached to the side dome portion of the first vibration member layer and the second vibration member layer, and made of the same material as that of the first vibration member layer.

[10] The sound converter of claim 7, wherein the diaphragm for the sound converter further comprises a third vibration member layer attached to the center dome portion of the second vibration member layer in an opposite direction to an attachment direction of the first vibration member layer, and made of the same material as that of the first vibration member layer.

[11] The sound converter of any one of claims 7 to 10, wherein the first vibration member layer of the diaphragm is welded to the voice coil in an opposite direction to an attachment direction to the second vibration member layer of the diaphragm.

[12] The sound converter of any one of claims 7 to 10, wherein the first vibration member layer to the third vibration member layer of the diaphragm are welded by heat and pressure.

[13] The sound converter of any one of claims 7 to 10, wherein the first vibration member layer is made of polyethylene or polypropylene, and the second vibration member layer is made of thermoplastic polyurethane.