JP2007043631A - Speaker using cone-type piezoelectric diaphragm - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new speaker system excellent in sound reproduction capability and using a cone-type piezoelectric diaphragm composed by combining a function of a piezoelectric diaphragm with that of an acoustic diaphragm. <P>SOLUTION: A cone-type diaphragm having a uniform thickness is formed by applying a drawing technique to a metal disk having a uniform thickness. A seamless integrally-molded cone type piezoelectric diaphragm is manufactured by bonding a piezoelectric ceramic onto both faces of a disk part after accurately finishing the thickness of the disk part and that of a cone part so as to be different in dimension by making full use of a chemical treatment technique. By this, it is possible to achieve the speaker having almost no noise, excellent in efficiency, and also, excellent in sound reproduction capability over a wide band without damaging metal characteristics. It is also possible to solve the problem that the conventional speakers are either of a periphery support type speaker used by supporting the periphery and a node support type speaker or the like used by supporting nodes, however, the speakers in those types have a narrow reproduction band and can reproduce sound only in a certain fixed frequency band, especially, they can not obtain a sufficient sound pressure level in a low frequency band. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a speaker using a cone-type piezoelectric diaphragm as an electrode plate.

    Sound generator Japanese Patent No. 3565560     Acoustic piezoelectric vibrator and speaker using the piezoelectric vibrator International Patent (Taiwan) Registration No. 1000064 International Patent (USA) Registration No. 6088464   Speaker using piezoelectric vibrator Patent application H11052759   Piezoelectric Speaker Patent Application H11-172187   Piezoelectric Speaker Patent Application 2001-161192   Piezoelectric Speaker Patent Application 2001-321514   Method for manufacturing piezoelectric diaphragm for use in piezoelectric speaker Patent application 2001-361564

Conventionally, as a method for transmitting the vibration of the piezoelectric diaphragm (piezoelectric vibrator) to the acoustic diaphragm, a method of fixing or bonding the acoustic diaphragm directly to the piezoelectric diaphragm has been performed through a connecting rod.
The present invention provides a method for efficiently transmitting vibrations of a piezoelectric diaphragm directly to an acoustic diaphragm. Conventional piezoelectric speakers have excellent reproduction capability in the middle and high sound ranges, but have the disadvantage that the amplitude obtained in the low sound range is small and the sound pressure level is extremely small. An object of the present invention is to solve such problems of the prior art, and an object of the present invention is to improve reproduction capability in a low sound range by integrating a piezoelectric diaphragm and an acoustic diaphragm.

  In the present invention, after a metal disk is drawn, a cone-type diaphragm in which a finished piezoelectric diaphragm and an acoustic diaphragm are integrated is processed to a predetermined thickness by chemical treatment. Further, a piezoelectric ceramic is bonded to the surface of the circular portion of the diaphragm (bimorph or unimorph type) to complete a cone type speaker unit.

  According to the present invention, a cone-type diaphragm can be formed by a spatula drawing technique without damaging the characteristics of the metal plate, and a cone-type diaphragm can be formed integrally with a chemical processing technique with a high precision to a predetermined dimension. is there. Further, by using the cone-type piezoelectric diaphragm manufactured by the integral molding process, it is possible to provide a speaker that reproduces a sound with high efficiency, low noise, and sharpness.

(1) The cone-type piezoelectric speaker of the invention is composed of a metal disk portion and a cone portion, and can be integrally formed without any loss of the metal characteristics and without a seamless process by drawing and special chemical treatment technologies. A precise vibration-free diaphragm can be manufactured.
(2) The improvement of the sound pressure level in the low frequency range, which is the object of the invention, and the improvement of the sound reproduction capability in the wide band are key points for speaker development. The required sound pressure level and frequency band are the electrode plate and piezoelectric ceramics. It can be designed by changing the combination of dimensions such as a damper.

  As a result of adopting and manufacturing the mini component stereo, compared with the electrodynamic type (dynamic speaker), a high quality reproduction sound having excellent responsiveness especially in the mid-high range was obtained. Moreover, the low frequency range of 60 Hz to 150 Hz, which has been said to have been impossible to reproduce with a piezoelectric speaker until now, has also been cleared, and this has become a great confidence for future sales.

  The car audio speakers currently being researched and developed are considered to be usable as speakers for mini-components and medical devices. To date, we have produced and sold more than 2 million medium- and high-frequency piezoelectric speakers. The feature of this patent is to realize a completely new type of piezoelectric speaker unit in which the vibrator and the diaphragm are integrally molded by fully utilizing the high performance and high sensitivity that are the characteristics of the metal diaphragm. In particular, it is a speaker that reproduces sound that is light, thin, and crisp, with low power consumption and no magnetic influence, and is considered to be very marketable.

Embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows a circular metal plate of uniform thickness.
FIG. 2 shows a cone-shaped diaphragm having a uniform thickness obtained by manufacturing a circular metal plate by spatula drawing.
FIG. 3 shows a cone-type diaphragm in which a cone-type diaphragm is chemically treated, and the thickness of the disk portion and the cone portion (thinner than the disk portion) is finished to a predetermined dimension.
FIG. 4 shows a cone-type piezoelectric diaphragm in which piezoelectric ceramics 4a are bonded to both sides of a disc portion of a cone-type diaphragm (FIG. 3).
FIG. 5 shows a speaker system using the cone type piezoelectric diaphragm of the present invention. By applying a voltage to the piezoelectric ceramic, vibration is excited in the disc part of the cone-type diaphragm, and part of the vibration propagates to the cone part. A part of the vibration is transmitted to another circular diaphragm 5b through a connecting rod (or stat) 5a. 5c is a rubber edge devised so as not to obstruct the movement of the diaphragm as much as possible, and also serves as a damper and is joined to the housing 5d. This improves and flattens the sound pressure level over a wide band. Reference numeral 5e denotes a circular hole for extracting the internal radiated sound, thereby further improving the sound pressure level.
FIG. 6 is a front view of the speaker system.

  Metal material disk according to an embodiment of the present invention   Cross-sectional view of cone-shaped diaphragm after spatula drawing according to an embodiment of the present invention   Sectional view of cone diaphragm after chemical treatment according to an embodiment of the present invention   3 is a cross-sectional view of a cone type piezoelectric diaphragm in which piezoelectric ceramics are bonded to the disk portion of the diaphragm of FIG. 3 according to an embodiment of the present invention.   4 is a cross-sectional view of a speaker system using the cone-type piezoelectric diaphragm of FIG. 4 according to an embodiment of the present invention.   Front view of speaker system

Explanation of symbols

4a: Piezoelectric ceramics
5a: Connecting rod (or stat)
5b: Circular diaphragm
5c: Rubber edge
5d: Case
5e: Round hole

Claims (4)

  Cone-type electrode plates are molded using special drawing technology for metal discs.   The metal disk is formed into a cone-shaped electrode plate, and the chemical processing technology is used to form the metal disk part and the cone part into different dimensions. The cone-type electrode plate can be integrally molded without impairing the characteristics.   Piezoelectric ceramics are bonded to the surface of the disk part of the cone-shaped electrode plate formed and processed in the preceding items 1 and 2 (bimorph or unimorph type), and the disk part of the electrode plate becomes the excitation part, and the disk part and the cone part further An integrated piezoelectric speaker that serves as a diaphragm.   A speaker that uses a urethane rubber edge that doubles as a damper around the circular diaphragm and cone diaphragm to connect the diaphragm to the chassis, improving vibration displacement, sound pressure level, and flattening.

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