# Patent

## Title
Compound membrane and acoustic device using same

## Abstract

The present disclosure provides a compound membrane and an acoustic device including such a compound membrane. The compound membrane includes a polyarylate film, and a thermoplastic polyurethane elastomer attached to one surface of the polyarylate film.

## Background
FIELD OF THE INVENTION
The disclosure described herein relates to acoustic devices, and more particularly to a compound membrane used in such an acoustic device capable of providing sound.
DESCRIPTION OF RELATED ART
Nowadays, speakers and/or microphones often comprise compound membranes which are basically a combination of layers of different materials or just a mixture of different materials.
Generally, a membrane is formed by a single film or by hot pressing a piece of thermoplastic material, the rigidity of the membrane is not enough when vibrating. In addition, to increase the rigidity of the membrane, the usual method is to increase the thickness of the membrane. However, a membrane is formed by a single film, whose thickness of different portion are the same, as a result, the sound quality of the acoustic device is undesirable when the membrane vibrates.
The present disclosure is provided to solve the problems mentioned above.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an illustrative cross-sectional view of a compound membrane according to an exemplary embodiment of the present disclosure; and
FIG. 2 is an exploded view of an acoustic device using the membrane in FIG. 1.



DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
Reference will now be made to describe exemplary embodiments of the present disclosure in detail.
Referring to FIG.1, a compound membrane 1 comprises a central portion 13 and a peripheral portion 14 surrounding the central portion 13. The compound membrane 1 includes a polyarylate(PAR) film 11 and a thermoplastic polyurethane(TPU) elastomer 12 attached to the surface of the PEI film 11. The TPU elastomer 12 is attached to the PAR film 11 by adhesion or other feasible methods, for example, hot pressing bonding, or ultrasonic welding. The TPU elastomer 12 coveres the PAR film 11 completely.
In an alternative embodiment, the TPU elastomer may overlap the PAR film at a portion corresponding to the periphery portion. Another word, the central portion of the membrane is formed by the PAR film and the peripheral portion of the membrane is formed by the compound of the PAR film and the TPU elastomer.
FIG. 2 shows an acoustic device 2 comprising such a compound membrane 1 according to the exemplary embodiment of the present disclosure. The acoustic device 2 further comprises a frame 20, a york 20 received in the frame 20, a magnet 22 received in the york 20, a pole plate 23 attached to the magnet 22, and a coil 24 with one end thereof received in a gap formed by the yoke 20 and the magnet 22 and another end fixed to the membrane 1.
Compared with the related membrane, the compound membrane of the present disclosure has a higher rigidity and a better stability due to the compound of the TPU elastomer attached on the surface of the PAR film.
While the present disclosure has been described with reference to the specific embodiments, the description of the disclosure is illustrative and is not to be construed as limiting the disclosure. Various of modifications to the present disclosure can be made to the exemplary embodiments by those skilled in the art without departing from the true spirit and scope of the disclosure as defined by the appended claims.

## Claims

1. A compound membrane comprising:
a polyarylate film; and
a thermoplastic polyurethane elastomer attached to one surface of the polyarylate film; and
wherein the compound membrane comprises a central portion and a peripheral portion surrounding the central portion, the central portion is formed by a single layer of the polyarylate film and the peripheral portion is formed by the compound of the polyarylate film and the thermoplastic polyurethane elastomer.

2. An acoustic device comprising:
a compound membrane as described in claim 1.